After doing some reading on this, help me out and see if I understand this correctly.
If the gap between the rear of the case and the front of the recoil surface is too great (round seated to far into chamber), then as the primer is ignited, due to its own pressure, it pops itself out of pocket. After the powder is ignited, the rear of the case (with the unseated already struck primer) smashes back into the recoil face of the slide, flattening the primer and possibly the case head as well.
This happens because there is just too much room for the case to fly rearward willy-nilly without the aide of a recoil spring slowing it down. Is this correct?
This is one of the reasons shooting .40 S&W outta a 10mm is a no-no also, right....just too much of a gap and the case now becomes a rearward projectile (though for a very short distance)...?