riflelength

Riflelength, often written as rifle-length or rifles-length, is a term used in discussions of semi-automatic rifles, particularly AR-15/M16-style platforms, to describe the length of the firearm’s gas system rather than its overall exterior length. The classification refers to how far the gas port is located from the muzzle, which influences the timing of the action and the felt recoil.

In practical terms, riflelength denotes the longest gas system category. It is one of three common AR-15 gas-system lengths, alongside carbine-length and mid-length. Rough approximate ranges are: carbine roughly 7–9 inches from the muzzle, mid-length about 9–13 inches, and rifle-length around 15–20 inches. Rifle-length systems are typically paired with longer barrels, such as 20 inches or more, where the extended gas port timing results in a slower initial impulse.

Advantages of a rifle-length gas system include a smoother perceived recoil impulse and more gradual operating pressure, which can contribute to reliable cycling with longer or heavier barrels and under certain suppressor configurations. It can also reduce wear on some components due to lower peak gas pressure at the action. Disadvantages include increased overall length and weight, and potentially reduced reliability in short-barrel or specialized builds where gas timing is less favorable.

Notes: manufacturers may vary naming conventions, and some builds blend lengths or use aftermarket gas systems. The riflelength designation is primarily a framework for comparing gas-port timing and intended barrel length, rather than a strict measurement.