Yeah so the first time I had this issue, I was shooting Freedom Munitions factory reloads that were bought during the post-Sandy Hook era. Could have just been the trash ammo. But, that upper (Noveske) ended up having some other issues that may or may not have contributed.
The more recent experience has been over the last few months with a Criterion Core barreled upper shooting mostly MEN 56gr 5.56, which is good ammo. Lots of back and forth and trouble shooting to the point that Criterion re-barreled my upper and I just got it back a few days ago.
Long story short and in agreement with CF, if you have reasonably decent factory brass ammo and it’s happened more than once, there’s something else going on.
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