Rifle Glossary & Technical Definitions

The core mechanism that supports and operates the bolt and cartridge during loading, firing and extraction. An action is not the same thing as the inlet cut into a stock.

The shaped opening in a stock or chassis that accommodates a particular rifle action. A compatible inlet must match the action and its mounting features.

A fastener that secures a rifle action to its stock or chassis. Screw size, length and tightening torque depend on the firearm and mounting system.

A detachable magazine format based on the Accuracy International Chassis System pattern. Matching the general pattern does not guarantee compatibility with every action, cartridge or bottom-metal assembly.

A dovetail-style accessory rail used with compatible sliding clamps, bipods and tripods. Dimensions and clamp compatibility should be checked for the particular products.

The barrel's external shape and diameter along its length. Contour affects weight and determines clearance inside a stock or chassis.

The machined breech-end portion of a barrel that mates with the action. Its geometry depends on the rifle's barrel mounting system.

The contact interface between an action and stock. Bedding may be machined into the stock or formed with a cured compound to establish consistent support.

A rigid sleeve installed around an action screw to provide a stable compression path through the stock material.

The forward surface of the bolt that supports the cartridge case head when the action is closed.

The angular movement needed to unlock a bolt-action rifle. For example, a 60-degree lift describes rotation, not how far the bolt travels rearward.

Often refers to the bolt's fore-and-aft travel during cycling. The phrase is also used for bolt lift angle, so measurements should specify distance or degrees.

The projectile's downward displacement due to gravity during flight. Trajectory relative to the line of sight also depends on sight height and zero distance.

Rotation of the rifle to either side around the barrel axis. Cant can change the direction of point-of-impact error.

The length of a loaded cartridge from the case head to the forward tip of the seated bullet. It is not the length of the bullet alone.

The precisely machined portion at the breech of a barrel that contains and supports the cartridge during firing.

A structural rifle mounting system, commonly made from metal or composite material, that supports the action and provides mounting points for the stock and accessories.

The condition of a barrel before it has been warmed by recent firing. A cold-bore shot is the first shot from that condition.

A removable box-shaped ammunition magazine. A DBM-compatible action and stock may also require matching bottom metal or a magazine catch.

Recorded firing data, including sight corrections and conditions, used as a reference for future shots with a particular rifle and ammunition combination.

A mounting profile with angled sides used to retain a compatible sight, ring or clamp. Common dovetail dimensions are not interchangeable without checking the specification.

A magazine arrangement in which cartridges occupy two staggered columns in the body and converge to one feed position at the top.

The mechanism that pushes or strikes a cartridge case to send it out of the action after extraction. Designs include fixed blades and spring-loaded plungers.

A hook, claw or other gripping component that engages the cartridge case rim or extractor groove and withdraws the case from the chamber.

The distance between the ocular lens and the shooter's eye at which the scope delivers its intended full field of view.

A scope-reticle position in which the reticle changes apparent size with magnification, so its angular markings retain their values across the magnification range.

A barrel with clearance from the stock's fore-end rather than direct contact along that portion. Actual clearance must be checked under the relevant conditions.

The distance from the closed bolt face to the specified chamber datum surface. The datum location depends on the cartridge design.

Using an aiming point above the intended impact location to compensate for trajectory instead of changing the scope's elevation setting.

The measured distance from the trigger to the rear of the buttstock or recoil pad, commonly taken to its center.

An accessory attachment interface that uses elongated mounting slots and compatible hardware to secure rails and other accessories.

An angular unit equal to one-thousandth of a radian. One milliradian subtends approximately 3.6 inches at 100 yards.

An angular unit equal to one-sixtieth of a degree. One MOA subtends approximately 1.047 inches at 100 yards.

The direction a supported rifle naturally settles when the shooter is relaxed and not deliberately steering it toward the target.

Apparent movement of a scope reticle relative to the target when the observer's eye changes position. A parallax adjustment helps align the relevant optical planes.

A mounting rail with standardized profile and transverse slots for compatible scope mounts and accessories.

The place on a target at which the shooter intends the sighting system to be aligned.

The location where a projectile actually strikes the target.

A projection or contact surface designed to transfer recoil loads from the action to a stock or chassis.

A scope-reticle position in which reticle appearance remains generally constant as magnification changes; its angular subtensions are usually calibrated at a specified magnification.

The view of the aiming reference and target through the sighting system when the eye is correctly positioned.

Traveling below the local speed of sound. The speed-of-sound threshold varies with atmospheric conditions.

Traveling faster than the local speed of sound.

The axial spacing of neighboring thread crests. Metric threads typically state spacing in millimeters; inch-based threads commonly state threads per inch.

A turning moment applied to a fastener, commonly expressed in inch-pounds or newton-meters. Use the specification for the exact components being joined.

The barrel distance over which the rifling makes one full revolution. A 1:16-inch twist means one complete turn in 16 inches.

A mounting arrangement using angled support faces to locate an action. Suitability depends on the action geometry and the specific block design.

The action is the rifle mechanism that contains and operates the bolt and cartridge. The inlet is the shaped opening in the stock or chassis that accepts that action. Matching an inlet requires checking the exact action and mounting arrangement, not just the manufacturer.

No. Picatinny is a slotted mounting rail, ARCA is a dovetail-style clamp interface commonly used with bipods and tripods, and M-LOK secures accessories through compatible mounting slots. Adapters exist, but direct interchangeability should not be assumed.

Both measure angles used for scope adjustments and reticle references. One MOA subtends approximately 1.047 inches at 100 yards; one MRAD (mil) subtends approximately 3.6 inches at 100 yards. Neither is inherently more accurate. The important point is using a consistent unit for the reticle, turret and recorded corrections.

A 1:16-inch twist rate means the rifling completes one revolution over 16 inches of barrel length. Twist is one factor in projectile stability; the appropriate rate depends on projectile characteristics and firing conditions.

No. AICS-pattern identifies a general magazine format. Compatibility still depends on the action, cartridge, magazine dimensions and the specific chassis or bottom metal. Consult the manufacturers' fitment information for the exact combination.

This page explains terminology rather than supplying model-specific measurements. For verified dimensions, fasteners, torque values and compatibility, consult the relevant technical reference, including the CZ 457 reference where applicable. Confirm specifications against the current instructions for your exact firearm and components.