This one always has me scratching my head.
Many self loading rifles have a rotating bolt in a bolt carrier with a pin that rides in a cam track, like this.
Trying to imagine how this operates, I would have thought it would have been fine up until the bolt ended it's rearward journey, at which point the inertia of the bolt in the carrier would make it set back so that, when it arrived at the breech, the locking lugs would slam into the bolt locking shoulders from behind and not be able to enter the recesses. Carrier movement forward would just make things worse and you would end up with the lugs in locked position but on the wrong side of the locking shoulders. I can see how that is prevented in the AR by the tab at the end of the cam pin riding in a longitudinal slot, but what prevents it on the AK and weapons patterned after the AR15 like the G36?