Possible damage to lower receiver. I’m new to PA10 but not new to the AR15, I have built several. Ive never seen these marks before on an AR15. I put a KAK heavy short buffer in it and a Springco orange spring in it. It has less than 150 rounds thru it. It originally had the short PA10 buffer in it and PA10 spring. I put the heavier spring and buffer in because it seemed to be recoiling harder than it should (I have shot numerous .308 bolt guns and semi-automatics). I have shot it with the heavier buffer and spring and it functioned fine and recoil was reduced . My research indicates the damage may be from the bolt carrier group travelling back too far into the buffer tube. I have since added 2 quarters inside thw buffer tube but I haven’t fired it like that yet. Any advice would be greatly appreciated. Thanks in advance.
Remove the quarters as that isnt going to do anything. It seems you have a lower that doesnt hwve the bcg relief cuts that came with Gen3 lowers.
A stronger spring or limiting the gas via adjustable gas block would be what i try.
I have already put a springco orange spring in it which is heavier than the factory PA10 spring. I also didn’t receive the allen wrench to adjust the gas block from the previous owner. So you don’t think the quarters would be helpful at limiting the rearward travel of the bolt carrier? Anybody know of a heavier spring than a springco orange?
No. Quarters are only a trick for ar9s with bcg overtravel. You dont have that issue with ar15s and ar10 bcgs.
Do you think that using a heavier AR15 carbine buffer would work instead of running the shorter AR10 buffer? I’m failry certain that damage to the lower is from the bcg slamming into the lower. I may have to get online tomorrow and see what PSA says.
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Do not use an ar15 buffer with an ar10. Ar10 bcgs are longer which is why you need a shorter buffer. What you have is a bcg essentially “wearing in” the buffer tube threads. This is common with ar10s that dont have the relief cuts. If it truly worries you, contact CS tomorrow as they are not on the forums.
Thanks for your assistance guitar guy. I’m begining to wonder if I have a gen2 or gen3 lower. My understanding is that the gen3 had the relief cut. Not going tobe thrilled if it turns out to be a gen2 lower. So in summation you believe this to be cosmetic damage and nothing to be concerned about?
The only difference between gen 2 and 3 that i know of is the bcg cuts. Post some more pics so we can get a better view. Lower, bcg, etc.