AR 15 Gas port Locations

[bigloudvtwin]

Hey All, Turning a couple barrels from blanks (extensions fitted and headspaced already). Can't seem to find Hard, Dead nuts specs for gas port locations. They will be rifle length (20" and 5.56 Nato). I suppose I could use the gas block/tube for reference but that seems kinda cheese ball. There's gotta be a reference somewhere on this here interweb??? And before someone says it, Yes I have already figured out how to "clock" the port to align with the barrel pin.

 

[pontiac428]

Why does it seem cheesy to use the gas block for reference? The tenon shoulder location and your particular gas block's port location are all you need. You can measure those to the thou or better, whereas a design spec might have a .005 tolerance IF the parts you are using are mil spec.

Btw, welcome to the forum, neighbor!

 

[Bamban]

Here is a typical 20 inch barrel used in high power. The gas port location depends on the gas block used, either .275 or .300 from shoulder. I drill/ream the gas port at .300 from shoulder to accommodate any gas block gas hole.




Here is an example of gas block we use for service rifle, it is designed for gas port at .275 from shoulder. To install just run against the shoulder. With .300 barrel gas port location just put a feeler gauge in between shoulder and gas block.

https://www.whiteoakarmament.com/sh...as-block-for-service-rifle.html#header-search