View Full Version : need bigger gas port?

June 22, 2007, 17:50
At what length of barrel to you need to open up the gas port? I was thinking of shortening my barrel to 17" and I know if you shorten it to 16.25 you need to make the hole bigger, but will I have to?

June 22, 2007, 17:59
I recently did a para build with a 17" barrel. Initially kept the gas port dia. standard. The rifle wouldn't function even with the gas closed. Opened up the gas port to 7/64 (0.109375) and the rifle runs fine with a gas setting of 4 using 83 vintage SA milsurp ammo.

If you do a search on gas ports you'll find a boatload of info.

Hope that helps.

June 22, 2007, 18:31
You should only make it as big as you need to. Most experts agree you should not go above about .120", however. Once you reach the eighth-of-an-inch region, you are in danger of shaving bullet jacketing.