Plain Words

Glossary

The words you will see on this site, in plain language. Questions? See the FAQ or call the shop at 601-736-6112.

Rifle platforms and parts

AR-15: The most common rifle platform in the US. It chambers small rifle rounds such as 5.56 NATO and .223.
AR-10: The larger-frame cousin of the AR-15. It chambers bigger rounds such as .308 Winchester and 6.5 Creedmoor.
DPMS-style (also DPMS pattern): A widely used set of AR-10 dimensions. Parts built to this pattern fit each other across many makers.
Upper and lower receiver: The two halves of an AR rifle. The lower holds the trigger, grip and magazine. The upper holds the barrel and bolt.
Billet: A part cut from a solid block of aluminum on a CNC machine. Billet is known for a precision fit and a sleek look.
Forged: A part pressed into shape from heated metal in a die, then finished on a machine. Forged is the mil-spec standard and a proven design. Both billet and forged are good ways to make a receiver.
CNC: Computer numerical control. A machine that cuts metal by following a computer program.
Handguard: The cover around the barrel that you hold with your support hand.
Free-float: A handguard that does not touch the barrel, so it cannot push on it.
M-LOK: A slot pattern on modern handguards for mounting lights, bipods and other accessories.
Picatinny: A slotted rail, usually on top of a rifle, for mounting sights and optics.
Muzzle device: A part on the end of the barrel, such as a flash hider or a brake.
Flash hider (birdcage): A muzzle device that cuts the visible flash at the muzzle.
BCG (bolt carrier group): The moving part inside an AR that loads, fires and ejects each round.

Bolt actions

Bolt action: A rifle you load by hand: lift the bolt, pull it back, push it forward, lower it. Slower than a semi-auto, and valued for accuracy and simplicity.
Action: The part of a bolt rifle that holds the bolt and the barrel. Also called the receiver.
RTSA and RTLA: Round Top Short Action and Round Top Long Action. A short action fits shorter cartridges such as .308 Winchester and 6.5 Creedmoor. A long action fits longer ones such as .30-06 and .300 Win Mag.
Remington 700 footprint (also Remington 700 pattern): The most copied bolt-rifle layout. Many aftermarket stocks and chassis are made to fit it. Helanbak RTSA and RTLA actions fit stocks and chassis made for the Remington 700, so you can upgrade the action and keep your setup.
Chassis: A metal stock that holds the action. A common upgrade over a factory plastic or wood stock.
Barrel harmonics: A barrel flexes and whips a little every time it fires. Accurate rifles let the bullet leave at the same point in that motion every shot.
Chamber and reamer: The chamber is the part of the barrel where the cartridge sits. A reamer is the cutting tool that shapes it, like the cartridge in reverse.
Truing: Cutting an action's threads, bolt face and lug seat square to each other so the bolt runs straight.
Headspace: How snugly a cartridge sits in the chamber, measured from the bolt face to the part of the chamber that stops the case. A gunsmith checks it with gauges when a barrel is fitted, before the first shot. Watch: Before You Fire a New Barrel — Watch This →

Gas systems, steel and barrels

Gas system: How a semi-auto rifle uses a little gas from each shot to cycle the action.
Carbine, mid-length and rifle gas: Names for how far down the barrel the gas port sits. Longer systems generally cycle more gently. Mid-length is the common middle choice.
Gas block: The part on the barrel that sends gas from the barrel back to the action.
4140 steel: A common alloy steel used for barrels, gas blocks and other parts that need to be tough and take heat.
Twist rate (for example 1:7): How fast the rifling spins the bullet. 1:7 means one full turn in 7 inches. A faster twist steadies heavier bullets.
Match grade barrel: A barrel made and checked to tighter standards than a typical factory barrel.

Finishes

Hard-coat anodize: A hardened surface made on aluminum by an electrochemical process. It is part of the metal, not a paint. Aluminum only.
Cerakote: A ceramic-based coating that is sprayed on and baked. It comes in many colors and works on steel and aluminum.
Nitride: A surface hardening for steel parts such as barrels and bolt carriers. Usually dark gray or black. It wears well and resists rust.

Calibers and ammunition

5.56 NATO and .223 Wylde: The standard AR-15 round. A Wylde chamber is made to handle both 5.56 NATO and .223 Remington ammunition.
.308 Winchester and 6.5 Creedmoor: Two popular AR-10 and bolt-action rounds. See the caliber table on the Rifles page for what each is good for.
Rimfire and centerfire: Rimfire rounds such as .22 LR are small and inexpensive. Centerfire rounds such as 5.56 and .308 are larger and more powerful.
Varmint: Small pest animals such as groundhogs and prairie dogs. Varmint shooting means small targets, often at distance.
Muzzle brake and suppressor: Two different muzzle devices. The Suppressor Basics page explains both, and which bore size to choose.

Buying

FFL: Federal Firearms License, held by licensed gun dealers. Firearms ship to a licensed dealer near you, not to your house.
Form 4473 and NICS: The federal purchase form and the federal background check, both completed at the dealer when you pick up.
ATF: The Bureau of Alcohol, Tobacco, Firearms and Explosives, the federal firearms regulator. It approves NFA transfers such as suppressor purchases.
Class 3/SOT dealer: A licensed dealer who is also registered to handle NFA items such as suppressors. A suppressor transfers through one of these dealers.
NFA: National Firearms Act. The federal law that covers items such as suppressors. For current availability and transfer details, contact the shop.
OEM: Original equipment manufacturer. Making parts that go into another company's product.
CAD/CAM: Computer-aided design and computer-aided machining. The software used to draw a part and plan how to cut it.

Calibers by use are in the caliber table. New to suppressors? Read Suppressor Basics. Prefer to watch? See Learn.