6mm arc gas gun bolt lock back

[ARlife4me]

The only extra help would be an extra power spring, but only if using a full mass/full auto carrier.

 

[TRG65]

I had a lot of problems with my 6 ARC. To get things to consistently run, I went to a full mass carrier, H2 buffer and Tubbs recoil spring, but I wouldn't get lock back. I switched uppers to a Seekins because I found I was getting a .3 mil shift between barricade and bipod shooting and then the same load would lock back. I had run the prior upper/lower combination as a 223 and never had a problem with lock back.