i'd have to agree on different guns have different tolerances on what constituted a closed bolt and being able to fire.
i had to deactivate some unloaded but old primed 30-30 brass that a buddy gave me.. the brass needed to be sized .. not sure what it had been fired in.. but the empties would NOT chamber fully inmy savage 30-30 bolt gun.. I couldn't get the bolt handle ALL the way down.. and it would not fire at all... however.. i did manage to squeeze the cases into my marlin 336 lever gun, and while the lever didn't completely close either... with a lil hand squeeze pressure on the lever i could get it to fire and thus deactivate the brass so i could size them. ( that 336 may have had a more liberal chamber is what i heard as well.. )
in any case.. that non closed bolt lettingthe cocking piece move it and or a unseated primer may be the full issue.
last weekend I deactivated a fandfull of 222 someone gave me.. some of the primers were visibly too high.. most of those required 2 trigger pulls on my remmy 700 boltgun to get the primer to pop. 1 to seat, leaving a light impression,a dn the next to pop.
probably why the guy gave me them.. he may have been getting missfires and not knowing why and dumped his brass..