Gas blocks are a necessary and often overlooked component when building an AR-15. Gas blocks regulate how much gas is put back into the gas system, impacting the reliability and longevity of the rifle. We offer several different AR-15 gas blocks that are good alternatives to the normal A2/A1 style gas block. Shop our selection below!
Our front sight gas blocks feature a foldable front sight post that allows you to keep the sight out of the way as a backup aiming system without cluttering your normal sight picture. These gas blocks come with either a bayonet mount or a picatinny rail on the bottom.
Our low-profile gas blocks allow you to easily mount them under the hand guard on pistol, mid-length, or carbine-length gas systems. They come in several options that are secured by set screws or cap screws. We also carry a hinged option to fit around pinned and welded muzzle devices.
Railed gas blocks allow you to mount Picatinny-compatible accessories to your gas block. We offer gas blocks with Picatinny mounted on the top of the gas block, on the bottom (with folding front sight), and with rail sections on both the top and bottom.
A .750 gas block is the standard barrel diameter for an AR-15. This style is compatible with medium barrels, M4-style barrels, and HBAR barrels. The .750 block should be your primary gas block option with most off-the-shelf AR-15s unless they have a non-standard barrel, for example, bull barrels and pencil barrels. The majority of our gas blocks come in the .750 port size.
A .625 gas block works best on pencil or other lightweight barrel designs. This is because they have a smaller diameter than M4 or SOCOM profile barrels at the gas block mounting point.
Gas blocks funnel the excess gas from firing a round into the gas system. This is transferred to the bolt carrier which in turn cycles the gun.
An AR-15 or an AR-10/308 pattern rifle needs to have a gas block to function. The gas block is the bridge between the gas system and the barrel, allowing for gas to be put back into the system for it to cycle properly.
Beyond allowing the gun to cycle, gas blocks can provide solid mounting locations for sights and other accessories depending on the gas block style. This can range from A2 front sights to Picatinny compatible gas blocks.
You should get a gas block that is compatible with the barrel you are using. Most manufacturers will have the dimensions of the barrel at the gas block location allowing you to quickly find the gas block that is compatible with that barrel.
If you have a standard AR-15 barrel you will most likely use a .750 gas block. If you have a pencil barrel you most likely will use a .625 gas block. And if you are using a bull/target barrel a .936 gas block will work. Be sure to check the manufacturer’s specifications just in case.
If your muzzle device is permanently installed, you will need to purchase one of our 2-piece or hinged gas blocks. This includes our hinged-low profile gas block, two-piece gas block, and our front sight gas block options.
If the gas tube is structurally sound and not damaged, you do not need to replace your gas tube when switching to a new gas block. The roll pin may also be re-used if it is in good condition.
Check out our video below for instructions on how to install your gas block.
YHM® was founded in 1951 by Wallace Judd and James Graham, in an area of Massachusetts known locally as “Yankee Hill.” James had recently finished a tour of duty in Korea and saw an opportunity to help those he served by manufacturing firearms and accessories.
Through years of dedication and adaptation, YHM® has managed to keep those original goals in place while also becoming a full-service OEM Manufacturer.
Since 2013, Yankee Hill Machine has been owned and operated by the third generation of the Graham family-brothers, Chris and Kevin. Today, their mission is to offer high-end, durable products at an affordable price without sacrificing quality. All products are made in the USA and designed to exceed your expectations.
