AR-15 Complete Uppers

AR-15 Complete Uppers

Legacy Guns Armory carries a wide selection of AR-15 upper receivers! We carry uppers in calibers like 5.56x45mm, 300 Blackout, 9mm Luger, 22 Long Rifle, 6.5 Creedmoor, 50 Beowulf, and more!

How Direct Impingement Uppers Work

Let’s get into the gas systems of AR-15 upper receivers. Direct impingement AR-15s have a gas port drilled into the barrel, which is covered by a gas block attached to a gas tube. This system bleeds expanding gases out of the barrel when a cartridge is fired, re-routing some of the gas back into the action to facilitate cycling of the bolt carrier group. Generally speaking, the shorter the gas system, the higher the pressure and the quicker the rifle will cycle. Longer gas systems often deliver less recoil and a more comfortable shooting experience. However, longer gas systems may prove unreliable for lower-pressure loads. For low-pressure loads, a shorter gas system taps the gas sooner, ensuring reliable cycling of the action.

AR-15 Upper Gas System Lengths

Pistol Gas System: The Pistol gas system is designed for AR-15 pistols, subsonic ammo, and some short-barreled rifles (SBRs). It is most commonly found in very short barrels or in rifles designed for lower-pressure cartridges. Pistol-length gas systems are often found in 300 blackout uppers. Pistol-length gas tubes are around 6.7” and are usually on barrels 16” and under.

Carbine Gas System: The carbine gas system is battle-tested and delivers reliable cycling. Carbine gas system tubes are typically around 9.8” and are featured on AR-15 complete uppers with barrel lengths between 10 and 20 inches, depending on the caliber.

Mid-Length Gas System: With a slightly longer gas system than the Carbine, the Mid-Length offers a softer recoil impulse, the potential for enhanced reliability, and an extended lifespan for the parts of the rifle. Mid-length gas tubes are around 11.75” and are typically featured on 14.5” and 16” barrels but can be found on uppers with barrels between 11.5” and 18”.

Rifle Gas System: The Rifle gas system is longer, resulting in even milder recoil, improved accuracy, and prolonged parts longevity. It provides excellent performance for precision shooting and long-range engagements. Rifle Length gas tubes are normally around 15.125” and are most featured in 18” and 20” barrels.

Other Gas System Lengths: Other less-common gas system lengths also exist. The Intermediate gas system has a length that sits between mid-length and rifle length and is popular for 18” DMR-type rifles. Some manufacturers, such as Proof Research, feature gas systems with lengths designed to work with a specific combination of cartridge and barrel length. Often these unique barrels will include a gas tube of proper length, so be sure to check out the product information for each barrel.

Popular Complete Upper Receiver Manufacturers

AR-STONER: AR-STONER has gained popularity for delivering cost-effective AR-15 products without compromising quality. Their AR-15 complete upper receiver offering covers most cartridges like 5.56x45mm NATO, 300 Blackout, 223 Wylde, 350 Legend, 450 Bushmaster, and more!

Geissele: Geissele is renowned for manufacturing top-tier, high-performance AR-15 components. Their AR-15 complete uppers offering is led by their USASOC near clone upper.

CMMG: CMMG makes innovative AR-15 products with a focus on rifles and uppers. They offer uppers in more calibers than any other manufacturer. Their uppers are chambered in 5.56x45mm, 9mm, 22 LR, 308 Win, 6.5 Creedmoor, 300 Blackout, 350 Legend, 4.6x30mm, 5.7x28mm, 6.5 Grendel, and 6mm ARC.

Daniel Defense: Daniel Defense is synonymous with excellence and is a popular choice among recreational shooters, law enforcement, and military personnel. Their AR-15 Complete Upper Receivers are led by their MK18 and MK12 uppers, which are some of the most known and popular AR-15 uppers.

Colt: Colt’s legacy in firearm manufacturing speaks for itself. Colt produced the M4 for the United States military and carries over that same quality to their civilian AR-15 upper offerings.