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Quality, mil-spec AR-15 gas blocks and tubes for your custom upper receiver build.

The AR's gas system is the heart of the semiautomatic beast: It's responsible for cycling rounds, ramming the bolt carrier group back and forth, and ejecting spent brass. Installing a proper gas system on your AR is critically important. It'll guarantee you enjoy mild recoil, good accuracy and reliability, and a longer lifespan when it comes to all the parts in your upper receiver and buffer system.

Carbine Gas for Mil-Spec Builds

The carbine-length gas system is favored amongst 5.56 and .223 AR builders (and the military itself) because this it guarantees rounds will cycle in the worst possible conditions. We partner with top gunsmiths and major manufacturers to provide low-profile gas blocks and carbine gas tubes that are precisely machined from quality steel and fabricated to mil-spec standards.

What about pistol, mid- and rifle-length gas?

Excellent question! Need help picking your gas setup? Pistol-length gas systems are required for all subsonic 300 Blackout builds, and all other AR calibers configured with pistol-length upper receivers. That includes 5.56, .223, 9mm, and others.

Mid-length gas systems work well with 5.56 and .223 setups sporting longer barrels, like an 18" or longer setup. Rifle-length systems are required for most .308, 6.5 Grendel and 6.5 Creedmoor builds.

Want even more info? Read our detailed Guide to AR-15 Gas System.

DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.

We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, District of Columbia, Hawaii, New Jersey, New York, Rhode Island, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.