Hey Guys,
I now have a good balance between gas and recoil systems. However, I am still seeing the bolt over run the next round... then jam.
With reloads at 2.800 OAL, I can manually get/cause the bolt to run over the round as it fed from the magazine. If I let the magazine hang naturally via gravity, I can make it over run the case. If I support the magazine (push up on it from the bottom of the mag) it will not over run the case, then jam... so a very small tolerance between jam and not jam if the mag was being supported or not.
I then surmised that the OAL of the round (2.800) and the long style of the bullet in the case (6.5 Creedmoor), may be creating an excessive attach angle as the bolt stripped the case out of the magazine, that would allow the bolt to over run the round, thus causing the jam. Again, I was able to do this manually with some dummy rounds.
Next, I loaded some 6.5 Creedmoor rounds with a bullet (140 grn kSST Hornady) that called for a shorter OAL of 2.690". I was thinking from an angle of attach perspective, it would be less than the rounds at 2.800 and then not allow the bolt to over run the round. I tested (live fired) around 40 rounds, and it definitely helped.... but still occurred (3-4 rounds).
Thoughts?
I suspect the upper/lower is out of spec in some way and the mag is just not high enough to allow for 100% proper purchase of the bolt lugs on the case head.
I'm using PMAGS.
Not sure what to do at this point.... thanks.