View Full Version : M1a gas port sizes

February 3, 2010, 08:44 PM
I have shortened several M1a barrels for other gunsmiths that sent them to me, but I have never been involved in the gas port sizing.

How much does the standard gas port on a 22" barrel need to be opened up as the barrel gets shortened to 18"?

I did some searching here, but as usual, vbulletin search sucks...

Can anyone point me to a good thread where there is discussion about this topic?

February 3, 2010, 09:02 PM
I just went through my M14 NM Building guide put our by the USAMU.

It dosnt give the info you are looking for. I'll have to measure one of my barrels tomorrow in the daylight if someone dosnt answer your question.

February 3, 2010, 09:48 PM
The 18" barrels use the same gas port diameter as the 22" ones.

It's the 16" SOCOM model that uses a smaller gas port.