Played with this a bit last night some more and the issue for me seems to happen when there are over 20 rounds in the mag. I’m using CZC base pads and grams kit for P series mags, so 23 rounds in the mag is possible, with a CGW steel guide rod and 15# recoil spring. I shot some factory 147 FN American Eagle through it, some 124 blazer, and then some of my friend’s reloads that are round nose 147 but the OAL is a tad shorter. The shorter OAL seemed to help vs the factory.
I was planning on shooting this at a local match this weekend with the gun, so I’ll see how it does after Sunday. Also planning to shoot it the rest of the year.