Glossary

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Cartridge Anatomy & Dimensions

Cartridge Overall Length COALCartridge Anatomy & Dimensions

The length of a loaded cartridge measured from the base of the case to the tip of the bullet (meplat). Useful for fitting a magazine, but it varies with bullet shape.Example30-06 with a 168gr SMK at 3.330 in COAL: bullet sits 0.020 in off the lands in a chamber cut to the published standard. Magazines are usually built for 3.34 max. You can chase the lands by lengthening to 3.345, but the bullet won't feed.

Cartridge Base to Ogive CBTOCartridge Anatomy & Dimensions

The length from the base of the case to a fixed point on the bullet ogive, measured with a comparator. More repeatable than COAL because it ignores meplat variation.ExampleSame 30-06 / 168gr SMK: caliper-and-comparator measurement to the ogive = 2.660 in CBTO. Two boxes of the same lot each give CBTO 2.660 ± 0.002. COAL varies with meplat, so it never holds that tight.

HeadspaceCartridge Anatomy & Dimensions

The distance between the bolt face and the chamber feature that stops the cartridge (shoulder, case mouth, rim, or belt, depending on cartridge design). The chamber controls that position so the primer sits the correct distance from the bolt face. Excessive headspace can lead to case stretch or separation.

Case HeadCartridge Anatomy & Dimensions

The thick base of the cartridge case containing the primer pocket. It is the strongest part of the case and bears the rearward thrust of firing.

Case WebCartridge Anatomy & Dimensions

The transition zone just forward of the case head where the brass is still thick. Case head separations typically begin here as the metal thins from repeated sizing.

Case BodyCartridge Anatomy & Dimensions

The main cylindrical (or slightly tapered) section of the case between the web and the shoulder. It holds the bulk of the powder charge.

Case ShoulderCartridge Anatomy & Dimensions

The angled transition between the body and the neck on a bottlenecked cartridge. The shoulder is the headspacing datum on most modern bottleneck rounds.

Case NeckCartridge Anatomy & Dimensions

The narrow portion of the case that grips the bullet. Neck wall thickness and condition strongly influence neck tension and concentricity.

Case MouthCartridge Anatomy & Dimensions

The open end of the case where the bullet is seated. It is chamfered and deburred during case prep to ease bullet seating without shaving copper.

OgiveCartridge Anatomy & Dimensions

The curved forward portion of a bullet between the bearing surface and the meplat. The shape of the ogive heavily influences ballistic coefficient.

Bearing SurfaceCartridge Anatomy & Dimensions

The cylindrical, full-diameter portion of the bullet that engages the rifling. Length and uniformity of the bearing surface affect pressure and consistency.

BoattailCartridge Anatomy & Dimensions

A taper on the rear of a bullet that reduces base drag, especially at supersonic and transonic speeds. Common on long-range and match bullets.

MeplatCartridge Anatomy & Dimensions

The flat or rounded tip at the very front of a bullet. Meplat-to-meplat variation is one reason CBTO is preferred over COAL for measuring seated depth.

CannelureCartridge Anatomy & Dimensions

A knurled or rolled groove around the bullet (or sometimes the case) used as a crimping point. Helps prevent bullet setback in semi-autos and tube magazines.

CrimpCartridge Anatomy & Dimensions

A deformation of the case mouth onto the bullet to lock it in place. The two main styles are taper crimp (used for cartridges that headspace on the case mouth) and roll crimp (used with cannelured bullets, often for revolvers and lever guns).

Taper CrimpCartridge Anatomy & Dimensions

A crimp that gradually tightens the case mouth around the bullet without rolling it inward. Standard for semi-auto pistol rounds that headspace on the case mouth.

Roll CrimpCartridge Anatomy & Dimensions

A crimp that rolls the case mouth into the bullet cannelure. Used for heavy-recoiling revolver loads and tube-fed lever guns to keep bullets from walking under recoil.

Neck TensionCartridge Anatomy & Dimensions

The interference fit between the sized case neck and the bullet. Consistent neck tension is widely considered important for low-ES, low-SD loads.

ThroatCartridge Anatomy & Dimensions

The throat erodes with use and lengthens over the life of a barrel. It is the unrifled portion of the bore just forward of the chamber, where the bullet jumps before engaging the lands.

FreeboreCartridge Anatomy & Dimensions

Longer freebore reduces the initial pressure spike and allows more powder capacity; shorter freebore (seating bullets close to or into the lands) is a tuning approach used by some precision shooters to reduce bullet jump. It is the unrifled bore section between the case mouth and the start of the lands, through which the bullet travels before engraving.

Lands and GroovesCartridge Anatomy & Dimensions

The raised lands and recessed grooves cut as rifling inside the bore. The lands engrave the bullet and impart spin; the grooves define the bullet diameter the bore was cut for.

Twist RateCartridge Anatomy & Dimensions

How fast the rifling spins the bullet, expressed as one turn per N inches (e.g. 1:8). Faster twists stabilize longer, heavier bullets.Example6.5 Creedmoor 140gr ELD-M is happy in 1:8 twist (Sg ≈ 1.86 at sea level). Drop to 1:9 and Sg falls to ~1.4. That is marginal at altitude or in cold weather. An AR-15 with heavy 77gr SMK needs 1:7 or 1:8; 1:9 starts to keyhole.

Bullet WeightCartridge Anatomy & Dimensions

The mass of the projectile, in grains (1 grain = 1/7000 lb). Heavier bullets carry more momentum and energy at a given velocity and resist wind better; lighter bullets reach higher velocities for the same charge. Weight is a primary input to the ballistic and stability math.ExampleIn .308 a 175gr SMK holds velocity and bucks wind better than a 168gr past about 600 yd, at the cost of a little more drop up close, which is why the 175 is the long-range pick and the 168 the shorter-range one.

Bullet LengthCartridge Anatomy & Dimensions

The overall length of the projectile, in inches. With weight, diameter, and twist rate it drives gyroscopic stability: longer bullets need a faster twist. It also influences ballistic coefficient and seating depth.ExampleA 6.5mm 147gr ELD-M is about 1.44 in long and wants roughly a 1:8 twist to stabilize; a stubby 120gr bullet of the same caliber is happy in a slower 1:9.

Bullet Diameter vs. Groove DiameterCartridge Anatomy & Dimensions

Bullet diameter is the actual diameter of the projectile; groove diameter is the bore measurement at the bottom of the rifling grooves. The bullet should match (or very slightly exceed) groove diameter for a proper seal.

Case Capacity (H₂O grains)Cartridge Anatomy & Dimensions

Internal volume of a fired or sized case, traditionally measured in grains of water. Useful for comparing brass brands and predicting pressure differences with the same charge.

Firing CountCartridge Anatomy & Dimensions

How many times a lot of brass has been fired since it was new, or since the last anneal. Brass work-hardens and stretches with each firing, so tracking the count tells you when to anneal, trim, or retire a lot before necks split or case heads separate.

Ballistics

Target CardBallistics

A per-stage shot plan: an ordered list of targets, each solved to a dial or a hold off the RUNNING turret. Running means what is on the turret after the previous shot, not always the zero. Also called a range card, stage card, or dope card. LoadOut's Target Card tab (Ballistics) re-solves the whole list live as conditions change.ExampleStage with steel at 300, 550, and 700 yd: dial 1.6 mil for the 300, dial up to 3.2 for the 550, then HOLD 1.1 over for the 700 instead of dialing again. That saves a turret move, and the card lists each move in shooting order.

Minute of Angle MOABallistics

An angular measurement equal to 1/60 of a degree, roughly 1.047 inches at 100 yards. Used for scope adjustments and group size.Example1 MOA at 100 yd = 1.047 inches. At 500 yd, 1 MOA = 5.24 inches. At 1000 yd, 1 MOA = 10.47 inches. To shift a group 6 inches at 600 yd, dial 6 / (6 × 1.047) = ~0.95 MOA.

Milliradian MILBallistics

An angular measurement equal to 1/1000 of a radian, roughly 3.6 inches at 100 yards or 10 cm at 100 m. Common on tactical and modern long-range optics.Example1 mil at 100 yd = 3.6 inches; at 1000 yd = 36 inches. To dial 0.5 mil right, that's 18 inches at 1000 yd, 1.8 inches at 100 yd. Most precision turrets click in 0.1 mil = 0.36 inch / 100 yd.

Ballistic Coefficient — G1 BC G1Ballistics

A measure of a bullet's drag relative to the G1 standard projectile (a flat-base, pointed reference shape). Convenient at common distances but tends to overstate performance for modern boattail bullets at long range.

Ballistic Coefficient — G7 BC G7Ballistics

BC referenced to the G7 standard projectile (a long boattail shape). Generally preferred for VLD and long-range bullets because it tracks their drag curve more accurately than G1.

Sectional Density SD (sectional density)Ballistics

A bullet's mass divided by the square of its diameter. Higher SD generally means better penetration and is one input to ballistic coefficient.

Extreme Spread ESBallistics

The difference between the highest and lowest velocity in a shot string. A simple, widely cited consistency metric, though SD is generally a more robust descriptor.

Muzzle Velocity MV / FPSBallistics

The velocity of the bullet as it leaves the muzzle, usually reported in feet per second (FPS). It anchors every external ballistics calculation downrange.

Energy Muzzle EnergyBallistics

The bullet's kinetic energy, in foot-pounds (ft-lbs): one-half mass times velocity squared, computed as weight (gr) × velocity (fps)² ÷ 450,400. It measures the work the bullet can do on impact and falls off downrange as velocity drops. "Muzzle energy" is this value at the muzzle.ExampleA .308 175gr bullet at 2600 fps carries about 2,627 ft-lbs at the muzzle (175 × 2600² ÷ 450,400); that energy falls steadily downrange as the bullet slows.

Sight HeightBallistics

The vertical distance from the bore centerline to the optic (or sight) centerline, in inches. A scoped rifle is typically about 1.5 to 2.0 in. It sets the sight-over-bore geometry, the small angle between the bore and your line of sight. That angle shapes the near trajectory and tells the solver where the bullet crosses your line of sight.ExampleWith a 2.0 in sight height and a 100 yd zero, the bullet starts 2 in below the line of sight, crosses it once near the muzzle (roughly 25 to 40 yd depending on the load), and crosses again at 100 yd.

Time of Flight ToFBallistics

The elapsed time from muzzle exit to target impact, in seconds. Time of flight drives both spin drift and Coriolis calculations: longer ToF means more time for Earth's rotation and gyroscopic precession to deflect the bullet.Example6.5 Creedmoor 140gr ELD-M at 2710 fps: ToF at 500 yd ≈ 0.64 s, at 1000 yd ≈ 1.46 s.

TransonicBallistics

The velocity range from roughly Mach 0.8 to Mach 1.2 (approximately 890 to 1340 fps at sea level), where aerodynamic behavior shifts dramatically as the bullet transitions from supersonic to subsonic. In the transonic zone a bullet experiences increased drag, reduced stability, and can yaw, causing the group to open.Example6.5 CM 140gr at sea level: goes transonic around 1280 yd. A bullet with Sg < 1.5 entering transonic is at high risk of key-holing.

Mach NumberBallistics

Bullet velocity expressed as a ratio to the local speed of sound. Mach 1.0 ≈ 1116 fps at 59 °F, sea level. Custom drag models (CDM) and measured-CDM solvers store drag coefficients at each Mach number because drag behavior changes with speed.ExampleA 6.5 CM 140gr ELD-M at 2710 fps ≈ Mach 2.43. At 600 yd it has slowed to ~1980 fps ≈ Mach 1.77.

Spin DriftBallistics

A small horizontal deflection caused by the bullet's gyroscopic spin (also called gyroscopic or yaw-of-repose drift). Direction follows the rifling twist; it becomes noticeable at long range. The size of the drift scales with the gyroscopic stability factor (Sg), so a quoted figure only means something if the Sg it assumes is stated.ExampleRight-twist barrel, Sg 1.7, 1.5 second time of flight at 1000 yd: bullet drifts about 0.2 mil (roughly 7.5 inches) to the right purely from gyroscopic precession. Faster twist = higher Sg = more spin drift; same with longer time of flight (slower bullets, longer ranges).

Coriolis EffectBallistics

The apparent deflection of a bullet caused by Earth's rotation during flight. Generally only relevant at extreme long range: noticeable at 800+ yards, significant at 1000+ yards.Example1000 yd shot due north at 40°N latitude with a 0.5 BC G7 bullet at 2710 fps: Coriolis pushes impact about 0.07 mil RIGHT, which is only 2 to 3 inches (Earth rotated under the bullet during its 1.5s time of flight). That same deflection is about 0.24 MOA, so check which angular unit a quoted Coriolis figure uses before you dial it. In the Northern Hemisphere this horizontal drift is always to the RIGHT no matter which way you fire. A south, east, or west shot still drifts about the same amount right. It flips to the LEFT only in the Southern Hemisphere.

YawBallistics

Angular misalignment between the bullet's axis and its line of flight. Excessive yaw degrades accuracy and can occur out of an unstable barrel-bullet pairing.

DragBallistics

The aerodynamic force decelerating the bullet in flight. Drag varies with velocity, air density, and bullet shape, and is captured indirectly by the ballistic coefficient.

Pejsa StabilityBallistics

A closed-form estimate of the gyroscopic stability factor (Sg): it takes the same bullet geometry as the app's default Sg formula, but with no temperature or pressure term. Sg ≥ 1.5 is generally considered stable for long-range work. The stability tile in the app computes and shows both figures. Because this formula divides by a slightly smaller factor, it always reads a few percent ABOVE the default figure for the same bullet, so a value below the default one is a sign something is off. LoadOut ships this figure as a cross-check only, since its closed form is unverified against the primary text. The default formula is the validated one.ExampleBerger 140gr Hybrid: bullet length 1.41 in, twist 1:8, MV 2750 fps, 59 °F. Pejsa Sg ≈ 1.65. Above 1.5 = stable for long-range work.

Miller Stability FormulaBallistics

The standard formula for the gyroscopic stability factor (Sg). Inputs: bullet length, diameter, weight, twist rate, and air density. Sg < 1.0 = unstable (bullet tumbles), 1.0 to 1.4 = marginal, ≥ 1.5 = stable, ≥ 2.0 = very stable. The aerodynamic-jump correction also derives from Sg.ExampleSame Berger 140gr at 1:8 twist, 2750 fps, sea level: Miller Sg = 1.57. Pejsa reads 1.65, a few percent higher as it always does for the same bullet. Both ≥ 1.5 → bullet is stable. If the rifle ran 1:9 twist instead, Miller drops to 1.24, which is marginal.

Form Factor (i7)Ballistics

Form factor i7 is the ratio of a bullet's drag to the standard G7 drag profile at the same Mach number. A bullet with i7 < 1.0 has less drag than the G7 standard (higher BC); > 1.0 has more drag (lower BC). The same bullet has different i-values relative to G1 vs G7.ExampleBerger 6.5 mm (.264) 140gr Hybrid Target: G7 BC = 0.319, sectional density = 0.287. i7 = SD / BC_G7 = 0.287 / 0.319 = roughly 0.90. Numbers below 1.0 = sleeker than the G7 standard at the same weight, less drag per the same SD.

Custom Drag Model CDMBallistics

A bullet-specific drag curve derived from Doppler radar measurement, replacing the G1 / G7 standard curve. CDM is more accurate than published BC at extreme range, but only available for popular bullets.ExampleBerger 140gr Hybrid Target's published Doppler-derived CDM at Mach 2.5 = drag coefficient 0.253. The G7 standard at Mach 2.5 = 0.270. The CDM's per-Mach values replace the G7 lookup in the solver, accurate at every velocity instead of one BC.

Range Day & Shooting

AzimuthRange Day & Shooting

The compass direction your rifle is pointed, measured in degrees clockwise from north (0° = north, 90° = east, 180° = south, 270° = west). Used by the ballistic solver for the Coriolis correction at long range, since Earth's rotation deflects bullets differently depending on which direction you fire.ExampleYou're shooting at a steel target due east. That's 90°: type 90 in the Shot Azimuth field. Firing direction mainly changes the VERTICAL part of Coriolis: an east shot lands slightly HIGH and a west shot slightly LOW at long range. The horizontal drift stays to the right in the Northern Hemisphere either way.

Incline / Decline AngleRange Day & Shooting

The slope of fire: positive uphill, negative downhill. Bullets drop with respect to GRAVITY (vertical), but you aim along the SLOPE, so a 30° uphill or downhill shot needs less elevation hold than a flat shot of the same line-of-sight distance. LoadOut solves the inclined trajectory directly, so the correction comes out of the solver itself, including the small uphill-vs-downhill difference.

Hold / HoldoverRange Day & Shooting

The amount you aim ABOVE the target to compensate for bullet drop, expressed in mil, MOA, or inches at the target. The opposite for wind is a "wind hold" or "lead." Holds are measured against the reticle's subtensions; you can either dial the turret OR hold off using reticle hash marks.Example6.5 Creedmoor 140gr at 800 yd needs 5.6 mil of drop compensation. You can dial 5.6 mil up on the elevation turret and hold center, OR leave the turret at zero and hold the 5.6-mil hash on the target. The bullet impact is the same.

DOPE DOPERange Day & Shooting

Data On Previous Engagement. The verified holds (drop and wind) for a specific load + rifle + atmosphere across a range of distances, typically captured in a chart or saved in an app. Live-fire DOPE is more reliable than calculator output because it bakes in your real bullet, your real barrel, and your real atmosphere.ExampleAfter a long-range session you log: 100 yd = 0 mil, 300 yd = 0.9 mil, 500 yd = 2.5 mil, 700 yd = 4.6 mil, 1000 yd = 8.8 mil. Next time you face wind 5 mph from 3 o'clock at 600 yd, you dial 3.4 mil up + hold 0.5 mil right (into the wind) and trust the dope.

Zero RangeRange Day & Shooting

The distance at which the bullet's trajectory crosses the line of sight on the way down: where the rifle is sighted in to hit point of aim. Every drop and wind hold is computed relative to it: at the zero range you hold dead center, and past it you hold or dial for drop.ExampleWith a 100 yd zero the rifle is dead-on at 100 yd; from that zero a 6.5 Creedmoor 140gr load needs about 0.9 mil of up-hold at 300 yd and about 2.5 mil at 500 yd.

DistanceRange Day & Shooting

The straight-line range to the target, in yards (or meters), measured from the muzzle. It is the primary input to every firing solution: drop, wind drift, time of flight, and energy are all computed for the distance you enter. On steeply angled shots the solver works from the horizontal (incline-corrected) distance, not the slope distance.ExamplePost a target at 500 yd and enter 500: the solver returns the drop, wind, and energy for that range. If the shot is steeply uphill, the effective distance for gravity is a bit less than 500 yd.

DropRange Day & Shooting

How far below your line of sight the bullet has fallen by the time it reaches the target, caused by gravity. Expressed in inches, mil, or MOA. The hold needed to compensate equals the drop: 9.8 MOA of drop means dial 9.8 MOA up.

Wind DriftRange Day & Shooting

How far the wind pushes the bullet off line by the time it reaches the target. Crosswind from your right pushes the bullet to your left and vice versa; tailwind / headwind have a much smaller effect than crosswind. Hold INTO the wind to compensate.

LeadRange Day & Shooting

The amount you aim AHEAD of a moving target so the bullet arrives where the target is going, not where it is. Equals target speed × time of flight. A walking person at 600 yd needs roughly 1.7 mil of lead with a typical match load.Example6.5 Creedmoor 140gr ELD-M at 2710 fps: 1000 yd time of flight = 1.46s. Lead for a 4 ft/s walking target = 4 ft/s × 1.46 s = 5.84 feet, which is 70 inches; about 1.9 mil of horizontal lead at that range. Mind the units: feet per second times seconds gives FEET, not inches.

Cant CorrectionRange Day & Shooting

Cant is any roll of the rifle around the bore axis. When the rifle is canted, dialing elevation up no longer goes straight up: it shifts impact horizontally as well as vertically. The cant correction adjusts the displayed hold so it matches what you see through the scope. A bubble level on the scope or rail keeps the reticle vertical; the phone's gyro reads cant in real time.Example5° rifle cant + 8 mil of dialed elevation at 1000 yd: impact moves about 0.7 mil sideways (8 × sin 5°). Level the reticle to zero out cant; the in-app cant tile reads cant from the phone's gyro and warns you when it exceeds 1°.

Aerodynamic JumpRange Day & Shooting

A small VERTICAL component of wind drift caused by the bullet briefly tipping into the wind as it leaves the muzzle. At long range it is usually a few tenths of a mil, small but real.Example10 mph crosswind from your right + Sg = 1.7 (a typical 6.5 Creedmoor 140 ELD-M) out of a right-twist barrel: aero jump adds about 0.1 mil UPWARD displacement at 1000 yd. A wind from the left moves the impact down instead. Small, but visible at extreme range.

Station AltitudeRange Day & Shooting

Your physical height above sea level at the firing point. It is what a map, a GPS or a phone altimeter gives you, and it is an INPUT: the solver uses it to work out the air pressure where you are standing, and from that your density altitude. It is not the same thing as density altitude, and the two are usually thousands of feet apart on a warm day. If you are used to reading DA off a meter, enter it in a field labeled Density Altitude, never here.ExampleYou are shooting at 5000 ft above sea level on a 90 °F afternoon. Your station altitude is 5000 ft. That is where you are standing. Your density altitude is about 8400 ft, because the hot thin air behaves like air 3400 ft higher up. Typing 8400 into station altitude would tell the solver you had climbed another 3400 ft, and it would give you a confidently wrong hold.

Density Altitude DARange Day & Shooting

A single number that summarizes how "thin" the air is, expressed as the altitude in the standard atmosphere with the same density as your current conditions. High DA (hot, low pressure, humid, high elevation) means less drag, less drop. Many shooters track DA on their data card so they can pull a single hold for the conditions.Example59 °F, 29.92 inHg, 0 ft elevation = 0 ft DA (sea level). 90 °F, 24.5 inHg, 5000 ft elevation = 8400 ft DA. The bullet travels through "thinner air" at 8400 ft DA, less drag, less drop: a 1000 yd shot drops about 1 mil less than at sea level.

Station PressureRange Day & Shooting

The actual barometric pressure at your shooting location, NOT corrected to sea level. Weather reports usually give sea-level-corrected pressure (~30 inHg even in Denver); your ballistic solver wants the raw station value (~24 inHg in Denver). A handheld weather meter reads station pressure directly.ExampleYour weather meter reads 24.6 inHg at the firing line in Denver. The TV weather report says 30.05, but that's been corrected to sea level. Use the 24.6 station pressure in your solver, not 30.05.

Air TemperatureRange Day & Shooting

The ambient air temperature at the firing point. It is the largest single driver of air density: hot air is thinner, so the bullet meets less drag and drops less. This is NOT the same as powder temperature sensitivity: that is what the heat does to your CHARGE, changing muzzle velocity before the bullet ever leaves the barrel. Both matter on a hot day, but they are separate effects, and the solver takes this one as an atmosphere input.ExampleA 1000 yd load zeroed on a 40 °F morning will hit high in the afternoon at 90 °F, because the thinner hot air lets the bullet carry. If your ammunition is also temperature-sensitive, the higher muzzle velocity adds to that on top.

Relative HumidityRange Day & Shooting

How much water vapor the air is holding, as a percentage of the most it could hold at that temperature. It works the opposite way to most people's intuition: humid air is LESS dense than dry air, because a water molecule is lighter than the nitrogen or oxygen it displaces. So high humidity means slightly less drag, not more. The effect is real but small. Temperature and station pressure matter far more, so enter it and move on.ExampleGoing from 0% to 100% humidity at the same temperature and pressure changes drop by well under a tenth of a mil at 1000 yd. Temperature and station pressure move the solution many times more.

ICAO Standard AtmosphereRange Day & Shooting

The reference atmosphere used as the baseline for ballistic tables: 59 °F, 29.92 inHg sea-level pressure, 0% humidity (dry air), 0 ft elevation. When you have no measured environmental data, the solver uses ICAO standard so the answer is at least defensible, but real conditions can shift drop by 0.5+ mil at 1000 yd.

Wind Direction (from convention)Range Day & Shooting

Wind direction is reported as the direction the wind is blowing FROM, in degrees. A 90° wind is from your right (east in absolute terms), pushing the bullet to your left. Many ballistic apps also accept "clock position": 3 o'clock is the same as 90°.

Magnetic DeclinationRange Day & Shooting

The angle between true north (geographic) and magnetic north (compass-reads). Varies by location, counting east of true north as positive: about -14° (14° west) in Maine, near 0° in the central US, about +14° (14° east) in Washington state. Coriolis math wants TRUE north, so the solver applies declination to convert the phone's magnetic-compass azimuth into a true bearing.

LatitudeRange Day & Shooting

Your location's degrees north or south of the equator. Coriolis deflection scales with latitude: strong near the poles, zero at the equator. The solver uses this for the Coriolis correction along with shot azimuth.

GroupRange Day & Shooting

A cluster of shots fired at the same aim point under the same conditions. The "group size" usually means extreme spread: center-to-center of the two widest impacts. A small group means the rifle, load, and shooter are consistent; the absolute position of the group is a separate question (zero / point of impact).

Impact Standard Deviation (σ) σ horizontal / σ verticalRange Day & Shooting

Per-axis spread of your impact group on the target: the population standard deviation of each shot's horizontal (or vertical) offset from the group centroid, in inches, computed over the shots you actually plotted (divide by N, not N−1). A tighter σ means a tighter group on that axis. Not the same statistic as velocity SD, which measures chronograph fps variation across a string.Example5 shots land at horizontal offsets −0.6, −0.2, 0.0, +0.3 and +0.5 in from the group centroid. σ horizontal = √(Σdx²/N) = √(0.74/5) ≈ 0.38 in. A σ vertical noticeably larger than σ horizontal usually points at velocity spread or vertical stringing rather than wind.

Group MOARange Day & Shooting

Group size expressed in minutes of angle, normalizing across distance. A 1-inch group at 100 yd is roughly 1 MOA; the SAME rifle's group at 200 yd would be ~2 inches but still 1 MOA. Useful for comparing groups fired at different distances.Example10 shots at 600 yd, extreme spread (center-to-center of the two widest impacts) = 6.5 inches. 6.5 / (6 × 1.047) = 1.03 MOA. A 1 MOA rifle at 600 yd.

Mean Radius MRRange Day & Shooting

The average distance from each shot to the group's center (centroid). More statistically meaningful than extreme spread because it uses every shot, not just the two outliers. Published precision-benchmarking methodology recommends MR over ES. Used in both group analysis on the range and per-charge statistics in load development.Example5 shots at 100 yd, distances from group centroid: 0.4, 0.5, 0.5, 0.6, 0.7 inches. Mean radius = (0.4 + 0.5 + 0.5 + 0.6 + 0.7) / 5 = 0.54 inches. Smaller MR = tighter group; less sensitive to one outlier than ES.

CentroidRange Day & Shooting

The geometric center of a group of shots: the mean of every shot's X and Y coordinates. Useful for "zero adjustment": if the centroid is 1 inch high and 0.5 inch right, dial down 1 MOA and left 0.5 MOA.

Confidence Interval (90%) CIRange Day & Shooting

A statistical range you're 90% sure contains the rifle's "true" precision. Three-shot groups have wide CI bands (a 0.5 MOA group could be a 0.2 or 1.5 MOA rifle); 10-shot groups tighten the CI dramatically. Published precision-benchmarking methodology supplies CI tables so you can interpret a group size honestly.Example3-shot group of 0.5 MOA → 90% CI is roughly 0.2 to 1.5 MOA (a 0.5 MOA group could be a 0.2 OR a 1.5 MOA rifle, with 3 shots you can't tell). 10-shot group of 0.5 MOA → 90% CI is roughly 0.4 to 0.7 MOA.

Hit ProbabilityRange Day & Shooting

The probability your next shot lands inside the target outline, given your group size, range uncertainty, wind uncertainty, and muzzle velocity SD. A 95% hit probability at 600 yd on an IPSC silhouette is "first-round hit" territory; <50% is gambling.ExampleIPSC silhouette (18 in × 30 in) at 600 yd. Inputs: 1 MOA group, 12 fps MV SD, ±5 yd range error, ±2 mph wind error. The WEZ returns a hit probability per shot; widening the wind call to ±5 mph (you're guessing harder) always lowers it, because every added uncertainty widens the dispersion spread over the target. How far it drops depends on your bullet and muzzle velocity, so the app shows the per-source breakdown next to the number.

Weapon Employment Zone WEZRange Day & Shooting

A Monte-Carlo simulation that runs your shot N times against random samples of your input uncertainties (wind ±, range ±, group MOA, MV SD), and reports the percentage of simulated shots that hit the target. The output is a hit-probability curve as range increases.ExampleIPSC silhouette (18 in × 30 in) at 600 yd. Inputs: 1 MOA group, 12 fps MV SD, ±5 yd range error, ±2 mph wind error. The WEZ returns a hit probability per shot; widening the wind call to ±5 mph (you're guessing harder) always lowers it, because every added uncertainty widens the dispersion spread over the target. How far it drops depends on your bullet and muzzle velocity, so the app shows the per-source breakdown next to the number.

BC Standard Deviation σ_BCRange Day & Shooting

The shot-to-shot variation in effective ballistic coefficient across a box of bullets, caused by manufacturing tolerances in bullet length, ogive shape, and weight. A non-zero σ_BC means each bullet has slightly different drag, producing vertical dispersion at the target independent of MV spread.ExampleA premium match bullet lot with σ_BC 0.002 G7 contributes roughly 3 in of vertical dispersion per shot at 1000 yd.

True DOPERange Day & Shooting

Tuning the ballistic solver to match your rifle's REAL observed drops so its predictions line up with what actually hits at distance. You pick ONE axis, Muzzle Velocity or Drag Scale, and enter a few (range, observed come-up) points. The app solves the correction and saves it on the ballistic profile, so a profile trued once is trued everywhere it is used. Your published BC is left untouched.ExampleThe solver predicts 8.5 mil at 1000 yd but you actually hold 9.0. If your chronograph is untrusted, true Muzzle Velocity; if the model is off only at the far end, true Drag. Either way the profile now matches your real dope.

Muzzle Velocity TruingRange Day & Shooting

The Muzzle Velocity axis of True DOPE. The app solves for the muzzle velocity that makes the predicted drops match your observed drops, then uses that trued MV for the solution while keeping your original (nominal) MV so the change stays reversible. Best when the model is off across ALL ranges, usually because of a chronograph reading that runs a little high or low.ExampleYour chronograph read 2700 fps but every hold runs a touch low. Feed in a couple of long-range drops and the app trues MV to about 2745 fps; the whole trajectory shifts onto your dope.

Drag Scale FactorRange Day & Shooting

The Drag axis of True DOPE: a multiplier on the bullet's drag (default 1.000 = no correction) that pulls the far-range trajectory onto your real drops WITHOUT touching the published BC. The app solves for the factor that matches your observed drops. Best when the model tracks well up close but drifts only at distance. Sometimes written "DSF / drop scale factor."ExampleYour load matches out to 600 yd but prints low past 900. Feed in a couple of far drops and the app sets a Drag Scale near 1.02; the near dope is unchanged and the far dope now matches.

Optics & Reticles

ReticleOptics & Reticles

The aiming pattern inside the scope: crosshairs, dots, hash marks, or a mil grid. Modern precision reticles are "tree" or "Christmas tree" patterns with hashes for fast holdover; hunting reticles are simpler (BDC dots or duplex crosshairs).

First Focal Plane FFPOptics & Reticles

The reticle is in front of the scope's magnification optics, so it grows and shrinks WITH the magnification. A 1-mil hash always represents 1 mil at every magnification. Standard for precision rifle scopes: dial up to a closer view, hold-offs still work without math.Example10× magnification + a 1 mil hash on a FFP reticle: hash subtends exactly 1 mil at the target. Switch to 25×: same hash STILL = 1 mil. Holdovers work without math at any zoom.

Second Focal Plane SFPOptics & Reticles

The reticle is behind the magnification optics, so it stays the same visual size regardless of zoom. The labeled subtension only matches at ONE specific magnification (usually max). At lower magnifications the math doesn't work, so SFP scopes are usually used at one fixed power for hold-off.ExampleSFP scope rated for hold-off at 10×: 1 mil-marked hash IS 1 mil at 10×. At 5× the same hash visually represents 2 mil at the target (because the target image is half the size of 10×). Math required if you hold off at non-rated power.

SubtensionOptics & Reticles

How much angular space (in mil or MOA) a feature on the reticle covers. A "0.2 mil hash spacing" subtension means each minor hash mark on the reticle represents 0.2 mil. Subtensions are how you translate "the impact landed two hashes low" into a usable correction.

Tube DiameterOptics & Reticles

The outer diameter of the scope's main tube: typically 1 inch, 30mm, 34mm, or 35mm/36mm on premium tactical scopes. Larger tubes give more elevation/windage travel but require larger scope rings.

Objective LensOptics & Reticles

The front lens of the scope, in mm. Larger objectives gather more light (better in low light) but the scope sits higher above the bore and is heavier. 50 to 56 mm is common for precision scopes; 32 to 44 mm for hunting / general purpose.

Click ValueOptics & Reticles

How much the impact shifts per detent of the elevation or windage turret. Common values: 1/4 MOA, 1/8 MOA, 0.1 mil, 0.05 mil. The smaller the click, the finer the adjustment, but more clicks per mil means more turret rotation for the same dial.

Travel per RotationOptics & Reticles

How many MOA or mil are in one full turn of the elevation turret. 10 mil per turn is standard on a precision turret; 25 MOA per turn on the MOA equivalent. Affects whether a 1000-yd hold needs one rotation or two, and how easy it is to lose track of which "level" you're on.

Max Elevation / WindageOptics & Reticles

Total adjustable travel of the turrets, usually expressed in mil or MOA. More elevation = able to dial farther distances without holdover. A 30 mil scope reaches significantly farther than a 12 mil scope on a typical 6.5 Creedmoor.

Eye ReliefOptics & Reticles

The distance behind the eyepiece where you get a full, clear sight picture. Too close = scope-bite; too far = a black ring around the image. Precision scopes have ~3.5 to 4 in eye relief; magnum-recoil hunting scopes have more.

Parallax (optics)Optics & Reticles

When the reticle and target image are NOT in the same focal plane, moving your head shifts the apparent point of aim. Adjustable-parallax (side-focus or AO) scopes let you focus the target image at the reticle plane, eliminating this error. Critical for precision shooting past 200 yd.

Field of View FOVOptics & Reticles

How wide an area you can see through the scope at a given range, usually quoted in feet at 100 yd. Higher magnification = narrower FOV. A 4×24 hunting scope might show 24 ft at 100 yd; a 25×56 might show 4 ft.

Mil-dot ReticleOptics & Reticles

A classic tactical reticle pattern with dots spaced 1 mil apart along the crosshairs. Originally a Marine Corps design for ranging; modern descendants (mil-hash, mil-grid, Christmas tree) use small hashes instead of dots for finer holds.

Christmas Tree ReticleOptics & Reticles

A modern precision reticle pattern that adds a wide grid of holdover hashes BELOW the crosshair, narrowing toward the bottom, visually resembling a Christmas tree. Lets the shooter hold for both drop AND wind on the same reticle without dialing. The pattern class is common across current long-range tactical optics; LoadOut ships several mil and MOA tree archetypes.

Load Development

Mean VelocityLoad Development

The average muzzle velocity of a string of shots, in fps. Combined with standard deviation, mean velocity is the headline output of a chronograph session. Feed both into the solver for honest predictions.

MV Standard Deviation MV SDLoad Development

Sample standard deviation of muzzle velocity across a chronographed string. Match-grade is single-digit (≤ 9 fps); factory ammo is often 15 to 25 fps. SD compounds with range: 10 fps SD becomes ~1 ft of vertical at 1000 yd, alone. The acronym collides with Sectional Density, so context decides which is meant.Example6.5 Creedmoor at 2710 fps mean, 10 fps MV SD. At 1000 yd, the velocity spread translates to ~12 in (~0.3 mil) of vertical dispersion at the target, independent of any other error source. Halve SD to 5 fps and it drops to ~6 in.

Range UncertaintyLoad Development

How wrong your distance-to-target estimate could plausibly be, expressed as ± yards. Even a quality rangefinder may be ±5 yd at 1000 yd; an unsupported guess could be ±50 yd. The WEZ tool uses this as one Monte-Carlo input.

Wind UncertaintyLoad Development

How wrong your wind-call could plausibly be, in mph. Even experienced shooters call wind ± 2 mph on a clean day; ± 4 to 5 mph in gusty terrain. WEZ uses this to compute the horizontal half of the hit-probability ellipse.

Powder FactorLoad Development

Bullet weight (grains) × muzzle velocity (fps) ÷ 1000. Used by competition rules (USPSA, IDPA, Steel Challenge) to define minor / major / no-score thresholds. Reloaders pick a charge that comfortably exceeds the floor without overloading the case.

Optimal Charge Weight OCWLoad Development

Dan Newberry's load development method. Fire three rounds at each step of an evenly-stepped charge ladder, round-robin across the charges, and plot the vertical impact at the target. Look for a 'flat spot': a span of consecutive charges, sitting between the scatter nodes where groups open up and shift, whose group centers barely move up or down. That flat spot is the stable charge window where the rifle shoots consistently across a small range of charges. The charge in the middle of it is the OCW node, theoretically the most tolerant of small charge / temperature variation.ExampleStep 0.3 gr from 39.5 to 41.6 gr (8 charges, 3 shots each = 24 rounds). Vertical centers: 39.5 → 41.0 = -2.1 in, 41.0 → 41.3 = -0.1 in, 41.3 → 41.6 = -0.2 in. Flat spot is 41.0 to 41.6, OCW node ≈ 41.3 gr.

Audette LadderLoad Development

Creighton Audette's load development method (Precision Shooting magazine, late 1970s). Fire one round per charge, stepping the charge upward through the safe range, at long distance (typically 300+ yards). Look for vertical 'stacking' where consecutive charges land near each other on the target. That span is the accuracy node. Differs from OCW in that it uses one shot per charge at distance instead of three at 100 yards.ExampleStep 0.3 gr from 41.0 to 43.7 gr (10 charges, 1 shot each) at 300 yd. Three consecutive shots at 41.6, 41.9, and 42.2 land within 0.4 mil vertically of each other; the rest spread by 0.8+ mil. The 41.6 to 42.2 span is the node.

Satterlee 10-shotLoad Development

Scott Satterlee's chronograph-driven load development method. Fire 10 rounds, stepping the charge upward by 0.1 to 0.2 grains across the safe range, with a chronograph on every shot. Plot mean velocity vs charge and look for a 'plateau': a span of consecutive charges where the velocity barely climbs (≤ ~12 fps per step). The plateau is the velocity-stable node and is theoretically the least sensitive to small charge variation. Its statistical validity is debated, but it remains widely used in PRS and long-range rifle shooting.ExampleStep 0.2 gr from 40.0 to 41.8 gr (10 shots). Velocities: 2580, 2598, 2618, 2641, 2655, 2660, 2664, 2682, 2701, 2718 fps. Steps 5 to 7 (2655 → 2664 fps) climb only ~5 fps each, which is the plateau. Recommended charge: 41.0 gr (mid-plateau).

Seating Depth LadderLoad Development

Variant of charge-ladder load development that holds the charge constant and steps the cartridge base-to-ogive (CBTO) seating depth. Fire a small group at each depth and look for the seating depth that produces the smallest groups or lowest vertical. Tunes the bullet jump (or jam) into the lands. Often run AFTER a charge node has been chosen: first you find the powder, then you tune the seating.Example6.5 CM 140gr ELD-M, 41.5 gr H4350 fixed. Step CBTO from 2.250 to 2.270 in 0.005 in increments (5 depths, 5 shots each). Group sizes: 0.55 / 0.42 / 0.31 / 0.38 / 0.49 in. Best CBTO 2.260 in.

Expansion RatioLoad Development

In interior ballistics, the ratio of the total volume behind the bullet at muzzle exit (case capacity plus barrel bore volume) to the case capacity on its own. A high expansion ratio means the gas had more room to expand, extracting more velocity per grain of powder. Longer barrels and smaller cases have higher expansion ratios.Example6.5 CM (52 grH₂O) in a 24-inch barrel: expansion ratio ≈ 7.0×. In a 20-inch barrel: ≈ 6.0×. Four inches of barrel moves the ratio by about 1.0 for this cartridge. The shorter barrel gives up some velocity too, but how much depends on the powder and charge weight, so it is not a fixed number.

Interior-Ballistics EstimatorLoad Development

A simplified interior-ballistics computational method first published in 1962 (revised 1980). Predicts muzzle velocity and peak chamber pressure from a small set of inputs (case capacity, powder relative quickness, charge weight, bullet weight + diameter + COAL, barrel length). The same simplified model that backed the first generation of desktop reloading programs in the 1980s. Less accurate than full Lagrange-treatment simulators but ships in LoadOut's mobile Internal Ballistics Calculator with ±10% MV / ±15% pressure across the test corpus.

Internal BallisticsLoad Development

The science of what happens to the bullet WHILE IT IS STILL IN THE BARREL: pressure rising as powder burns, gas expansion accelerating the bullet, peak pressure typically reached within the first inch or two of travel. Distinct from external ballistics (trajectory once the bullet exits the muzzle). Internal-ballistics simulators (the empirical 1962-era estimator LoadOut ships, plus Lagrange-method simulators on desktop) predict muzzle velocity and peak chamber pressure from a hypothetical recipe.

Loading DensityLoad Development

The percentage of the case capacity that the powder charge occupies, by volume. Computed as charge weight ÷ (case capacity × powder bulk density). Higher loading density tends to give more consistent ignition. The estimator applies cleanly in the [10%, 110%] band. Below 10% (very low fill) you risk inconsistent ignition and erratic velocities; above 110% (compressed loads) the predicted pressure curve breaks down. Modern long-range rifle loads typically run 90 to 105% loading density.Example6.5 CM, 41.5 gr H4350, ~52.5 gr H₂O case capacity. H4350 bulk density ≈ 0.95 g/cc (extruded stick). Loading density ≈ 41.5 / (52.5 × 0.95) ≈ 83%, comfortably inside the calibrated band and mildly below "fill the case" territory.

Burn-CompletionLoad Development

Fraction of the powder charge that has been consumed (turned from solid grains into gas) by the time the bullet exits the muzzle. Internal-ballistics models compute it as part of the pressure / velocity prediction. A fast powder in a long barrel may reach 100% burn completion well before muzzle exit; a slow powder in a short barrel may exit at only 80%: the unburned powder ejects out the muzzle as visible flash. Useful diagnostic for matching powder burn rate to barrel length.

Group Extreme Spread Group ESLoad Development

The largest center-to-center distance between any two impacts in a group. The classic "group size" number, in inches or MOA. Easy to measure and easy to communicate, but volatile at small sample sizes: one flier dominates. Pair with mean radius for a more stable picture of the group. Distinct from MV ES (the velocity equivalent across a chronographed string).

Powder & Burn Behavior

Burn RatePowder & Burn Behavior

How quickly a powder converts to gas under chamber conditions. Faster powders peak pressure sooner and suit smaller cases; slower powders suit larger cases and heavier bullets.ExampleFor 9mm 124gr (small case, light bullet) you'd pick a fast powder like Titegroup or W231. For 6.5 Creedmoor 140gr (medium case, heavy bullet for caliber) a slower powder like H4350, RL-16 or Varget fills the case and peaks pressure at the right point in the barrel.

Extruded PowderPowder & Burn Behavior

Powder formed into small cylindrical sticks (also called stick powder). Generally meters less consistently through volumetric throwers than ball powder but is widely used in rifle loads.

Spherical (ball) PowderPowder & Burn Behavior

Powder formed into small round or flattened spheres. Meters very well through powder throwers and tends to be temperature-sensitive depending on the formulation.

Flake PowderPowder & Burn Behavior

Powder shaped into small flat disks. Common in shotgun and pistol loads; bulky, fast-burning, and meters acceptably in most measures.

Charge Weight gr (grains)Powder & Burn Behavior

The mass of powder in a single load, measured in grains (1 grain ≈ 0.0648 g). Reloading data is published in grains; never confuse grains with grams.

Pressure CUP / PSIPowder & Burn Behavior

Peak chamber pressure during firing, measured by transducer (PSI) or older copper crusher methods (CUP). Published industry standards set the maximum allowable pressure for each cartridge.

Pressure SignsPowder & Burn Behavior

Physical indicators of overpressure: cratered or pierced primers, ejector marks on the case head, sticky bolt lift, flattened primers, and case head expansion. They are unreliable on their own. Stay within published data.

Temperature SensitivityPowder & Burn Behavior

How much a powder's velocity and pressure shift with ambient temperature. Powders marketed as temperature-stable (e.g. Vihtavuori N500-series, Alliant Reloder 16/26, Hodgdon Extreme/StaBALL) are formulated to minimize this drift.

Compressed LoadPowder & Burn Behavior

A load in which the powder column is compressed by the seated bullet. Many published rifle loads are slightly compressed; heavy compression can affect ignition and seated depth stability.

BridgingPowder & Burn Behavior

A condition where powder kernels jam against each other and resist flowing through a drop tube, funnel, or case neck. Common with long extruded powders and small case necks.

Relative Quickness RQPowder & Burn Behavior

A powder's burn rate expressed as a single number, relative to a reference powder. Different sources use different references and different scales: Western Powders' chart uses Reloder 7 = 100; LoadOut's Internal Ballistics Calculator normalizes to IMR 4350 = 100. Higher RQ means faster (early peak pressure, lower MV in long barrels); lower RQ means slower (late peak, higher MV in long barrels). Used by the interior-ballistics estimator as the headline powder input.ExampleIMR 4350 = 100 (reference). H4350 = 95 (very slightly slower). Varget = 120 (notably faster, for shorter barrels and smaller cases). Reloder 26 = 56 (slower, for magnum cases and long barrels).

Primers

Boxer PrimerPrimers

A primer design with a single central flash hole and a self-contained anvil. Used on virtually all U.S. commercial brass and is what makes that brass reloadable.

Berdan PrimerPrimers

A primer design where the anvil is part of the case and there are two off-center flash holes. Common on European and military surplus brass; not practically reloadable with standard tools.

Small / Large Pistol / Rifle PrimersPrimers

Standard primer sizing. Pistol and rifle primers of the same diameter are not interchangeable: rifle primers have harder cups and different brisance to suit their applications.

Magnum PrimerPrimers

A primer with a hotter, longer-duration flame. Often called for with ball powders, very large cases, or cold-weather loads where ignition needs help.

Benchrest PrimerPrimers

A primer batch held to tighter manufacturing tolerances, marketed for precision shooters chasing low velocity SD. Real-world benefit is debated but common among match handloaders.

Primer Pocket Uniformity / DepthPrimers

A case prep step that cleans carbon out of fired primer pockets and optionally cuts each one to a uniform depth and bottom geometry. The goal is primers that seat squarely to a consistent depth, which can improve ignition consistency.

Primer Crimp / Crimp RemovalPrimers

Many military cases have a ring or stake crimp swaged into the primer pocket to retain the primer. It must be cut or swaged out before a new primer can be seated.

Primer Cup HardnessPrimers

The hardness of the metal cup containing the priming compound. Harder cups resist piercing in high-pressure or AR-pattern actions; softer cups are easier for light striker hits to ignite.

Brass & Case Prep

AnnealingBrass & Case Prep

Heating the case neck and shoulder to relieve work-hardening from repeated sizing. Done correctly, it extends case life and stabilizes neck tension.

TrimmingBrass & Case Prep

Cutting cases back to a consistent length after they grow from firing and sizing. Overlong cases can pinch into the throat and spike pressure.

Chamfer / DeburrBrass & Case Prep

Beveling the inside (chamfer) and outside (deburr) of the case mouth after trimming. A clean chamfer lets bullets seat without shaving jacket material.

Full Length SizingBrass & Case Prep

Resizing the entire case body, shoulder, and neck back toward factory dimensions. Reliable for semi-autos and any rifle where chambering has to be smooth and reliable.

Neck-only SizingBrass & Case Prep

Resizing only the neck and leaving the body fire-formed to the chamber. Often used by bolt-action precision shooters who keep brass with a single rifle.

Body DieBrass & Case Prep

A die that sizes the case body and bumps the shoulder without touching the neck. Used in conjunction with separate neck sizing setups (bushing dies, mandrels).

Shoulder BumpBrass & Case Prep

Pushing the case shoulder back a small, controlled amount (typically 0.001 to 0.003") relative to its fired position. Provides reliable chambering without overworking the brass.ExampleFired 6.5 Creedmoor case measures 1.553 in shoulder-to-base with a comparator. Size in your full-length die and re-measure: 1.551 in = 0.002" bump. Smooth bolt close, brass life maximized; bump 0.005" and you'll feel it loose, or skip the bump and the bolt fights you.

Mandrel SizingBrass & Case Prep

Setting final neck inside diameter by pulling or pushing a precise rod (mandrel) through the neck after sizing. Tends to give very uniform neck tension and good concentricity.

Case Capacity Weight SortingBrass & Case Prep

Weighing prepped, empty cases as a proxy for internal volume and grouping similar cases together. The relationship between weight and capacity is imperfect but often correlates.

Spring BackBrass & Case Prep

The small amount a sized case (or neck) elastically expands after leaving the die. It is why bushings are typically chosen a couple thousandths under final desired diameter.

Reloading Process

Decapping / DeprimingReloading Process

Punching the spent primer out of a fired case, usually with a decapping pin in the sizing die or a dedicated decapping die. Often the first step of case prep.

Sizing DieReloading Process

A die that resizes a fired case toward chamber-ready dimensions. Comes in full length, neck, body, and bushing variants.

Seating DieReloading Process

A die that pushes the bullet into the case to a target depth. Micrometer-top seating dies give repeatable, fine seating-depth adjustments.

Crimping DieReloading Process

A die dedicated to applying a roll or taper crimp as a separate step from seating. Separating the operations often yields better consistency than crimp-while-seating.

Powder Dispenser / ThrowerReloading Process

A device that dispenses a measured charge of powder by volume (mechanical thrower) or weight (electronic dispenser). Volume-based throwers are fast; weight-based dispensers are precise.

Beam vs. Electronic ScaleReloading Process

Beam scales use mechanical balance and need no calibration drift management; electronic scales are fast and convenient but require warm-up, calibration, and protection from drafts. Many handloaders verify with both.

OAL Gauge / Hornady ComparatorReloading Process

Tools for measuring CBTO and finding the distance from the bolt face to the lands in your specific chamber. Essential for tuning seating depth.

Concentricity GaugeReloading Process

A fixture that measures runout of the loaded bullet relative to the case body. Helps diagnose dies, brass, and seating issues that produce crooked rounds.

ChronographReloading Process

An instrument for measuring projectile velocity. Common types include optical screens, magnetic (MagnetoSpeed), and Doppler radar units (LabRadar, Garmin Xero, Caldwell Velocimeter).

Load DevelopmentReloading Process

The process of working up a load by varying charge, seating depth, and components while observing pressure and group behavior. Common methods include ladder tests, OCW, the Satterlee 10-shot, and the Audette ladder.

Ladder TestReloading Process

A load development method where each shot uses a slightly larger charge, fired at a distant target to spot vertical clusters that suggest a stable charge window.

Velocity / Accuracy NodeReloading Process

A charge or seating-depth window where the load shrugs off small changes. That can show up in velocity (a flat spot on the velocity curve) or in accuracy (a stable group point of impact).

Firearm-Side

Barrel LengthFirearm-Side

Length of the barrel from breech to muzzle (or muzzle device shoulder, depending on convention). Longer barrels generally yield more velocity, up to the burn-rate limit of the powder.

ActionFirearm-Side

The mechanism that loads, locks, and unloads cartridges. Common types include bolt action, semi-automatic, lever action, pump, and break-open.

ChamberFirearm-Side

The rear portion of the bore that supports the cartridge during firing. Chamber dimensions are cut to a reamer print derived from the published standard.

Cartridge StandardsFirearm-Side

Industry standards bodies in the U.S. and Europe publish chamber, cartridge, and pressure specifications for each cartridge. The two specifications sometimes differ slightly for the same nominal cartridge, so a chamber cut to one standard may not match ammunition made to the other.

Free-floated BarrelFirearm-Side

A barrel that does not contact the stock or handguard along its length. Eliminates inconsistent stock pressure on the barrel and is a common precision feature.

BeddingFirearm-Side

How the action is mated to the stock or chassis. Common methods include pillar bedding (metal pillars for screw torque), glass bedding (epoxy fit), and V-block / chassis systems.

Velocity Loss per Inch (rule of thumb)Firearm-Side

A rough rule of thumb: cutting a rifle barrel typically loses on the order of 20 to 50 fps per inch, depending on cartridge and powder. Treat this as an estimate, not a prediction.