I wonder if your issues aren't chamber related. It just sounds like a short throat or carbon ring. I've got a 280ai that I run a bit over max and when it starts popping primers, I run a bore snake through it half a dozen times and it goes back to normal. Usually see that kinda stuff in new barrels. I think EC said that your throat wears the most in the first 200 rounds. Maybe after that your issues will go away.Most of the discussion in this thread is not about "failures".
My SFAR, for one, has never missed a beat feeding and ejecting everything I've fed it.
My complaint is the brass gets torn up even with range fodder and with commercial off the shelf power hunting rounds primers get popped and flattened. If I was running hand loads I'd question the ammo first but something is off with the rifle when you can't use commercial ammo without getting hints of catastrophic failure.
My SFAR has, so far, been "reliable". It just mangles brass.