how did you remove the primer crimp? Did you do it yourself? Always use a primer pocket swager, as these remove no metal from the case, the drill/auger types always remove metal , sometimes a dangerous amount.
I've never used those cases, so I cannot comment on a history of loading with them.
You might try using commercial cases, or even LC military cases that you've prepped yourself & see if the problem persists. Armalite AR' platform rifles are of excellent quality.
Was hoping Maury would chime in on this.
be safe, enjoy life, journey well
OFC, Mo. Chapter