Gunsmithing Blueprints/specs for turning barrel blanks into AR barrels?

[TresMon]

Ive done a bunch of bolt gun barrels but never AR barrels. I need to machine a 20" AR barrel and a 8.5" AR pistol barrel. Anybody know where I can get the specs for the locations of the gas ports, etc? Thanks.

Edit: I actually just need to know the gas port location for pistol length and a 20."
Thanks!

 

[81STFACP]

Here is a typical print for a 20 inch 223 barrel used in high power. The gas port is either .275 or .300 from the shoulder. The typical gas block mostly used in high power have the ports at .275 like this one from Whiteoak Armaments. https://www.whiteoakarmament.com/sh...750-clamp-on-gas-block-for-service-rifle.html

 

[TresMon]

Thanks so much. Have a print for an AR pistol barrel?

 

[flyer]

JSE has (or had) some "gunsmith special" .300 Blackout barrels with pistol gas.

That's a cheap way to get the dimensions and a barrel extension you can scavenge.

 

[81STFACP]

Thanks so much. Have a print for an AR pistol barrel?

Sorry, never mess with AR pistols.

 

[msalm]

With the barrel extension installed and the gas block/tube assembled, the Gas tube needs to extend past the rear of the bbl extension just shy of 1”. It’s probably right at an inch but I always put it at .995” or so. That measurement will allow you to figure out the gb shoulder location on a barrel for any length Gas tube... helps when making custom length tubes too.

 

[MarinePMI]

Check out Green Mountain Rifle Barrels' website. Pretty sure their AR barrels have a print listed with each of them....you just have to click on the "see more pictures" to see the prints.

This one is a 7.5" bbl

 

[GH41]

Ive done a bunch of bolt gun barrels but never AR barrels. I need to machine a 20" AR barrel and a 8.5" AR pistol barrel. Anybody know where I can get the specs for the locations of the gas ports, etc? Thanks.

Edit: I actually just need to know the gas port location for pistol length and a 20."
Thanks!

As cheap as AR components are these days you might want to look at just buying the barrels. Nothing wrong with doing it yourself but you cannot make money doing it. The exception might be if you have someone wanting something weird that you can't buy.

 

[TresMon]

With the barrel extension installed and the gas block/tube assembled, the Gas tube needs to extend past the rear of the bbl extension just shy of 1”. It’s probably right at an inch but I always put it at .995” or so. That measurement will allow you to figure out the gb shoulder location on a barrel for any length Gas tube... helps when making custom length tubes too.

Awesome, Thank you!