Rifle Gas Ejection/Lock Back/Gas Issue

**swampfox44** · 04-16-19, 16:59

I have a Colt 6920 carbine I just swapped out the 16" factory barrel for a Larue Tactical Stealth 20" rifle length gas barrel. I installed a new SLR Sentry 7.750" adjustable gas block and new rifle length gas tube. I've gone through all 15 settings on the GB and finally got ejection at #13 but, no lock back. Stepped up to #14 and #15. Better ejection, no lock back. I'm wondering if I need to enlarge gas port or try standard, non adjustable block. My test firing was done with 55gr Pmc Bronze to get me in setting ballpark but, I don't seem to be getting enough gas to fully cycle the bolt. Any suggestions are greatly appreciated. Thanks

**TomMcC** · 04-16-19, 18:12

My first thought was...why did you do that? I live in Ca. And wish I could get an intact 6920.

Are you sure the GB is installed correctly? Are you sure you're adjusting GB corrctly?

**Iraqgunz** · 04-16-19, 18:17

IMO 20" midlength is a non-starter. I wouldn't be surprised if the gas port is too small.

**swampfox44** · 04-16-19, 18:32

Originally Posted by TomMcC

My first thought was...why did you do that? I live in Ca. And wish I could get an intact 6920.

Are you sure the GB is installed correctly? Are you sure you're adjusting GB corrctly?

Barrel is dimpled for alignment of gas block, when adjusted all the way open, setting 15, its ejecting but, still not quite enough gas. Thinking gas port size may be too small.

**sig1473** · 04-16-19, 18:34

Looking at their website, the 20" is rifle length gas........

**swampfox44** · 04-16-19, 18:36

Originally Posted by Iraqgunz

IMO 20" midlength is a non-starter. I wouldn't be surprised if the gas port is too small.

I'm thinking gas port needs enlarging as well. If I'm at full open on gas block and still not enough gas then, step size up and try again.

**TomMcC** · 04-16-19, 18:46

Before you start drilling on your new barrel, measure the gas port...maybe a local gunsmith can help you there. I dont know off the top of my head what it should be, but others here do. If you have a fixed quality GB, try it.