Nah, the concern is more of the bolt travelling forward as you press the trigger, it picking up a cartridge from the feed lips and pushing it up the ramp, and then the cartridge getting stuck at a weird angle while being pushed towards the barrel where the firing pin slams into the primer before the cartridge was fully pushed into the chamber. then the cartridge explodes without being fully sealed and you have basically what is a glorified mini hand grenade going off in your hands. 

Open bolt fixed firing pin SMGs were notorious for that problem, but it was rare enough that WW2 armies just kept it as it is and accepted the fact that a sten or pps-43 would blow up once in a blue moon, but that was a preferable alternative than being without a weapon in the middle of a world war. 

But after WW2 everyone thought to themselves "yeah let's not randomly cripple some recruit's hands and only allow the firing pin to protrude when the cartridge is fully loaded and sealed"