You can most definitely inspect the chamber on those weapons. How do you think they eject the casing?
Sigh, "open bolt" they load as they fire.
They don't have a round in the chamber, bolt back chamber empty is "live" and ready to fire.
You will find this on many fully automatic weapons as sticking a round in a very hot chamber is a good way to set it off.
The firing pin is fixed and sets off the round with the moving of the bolt. You physically can't close the bolt with a round in the chamber without setting off and firing that round.
But according to you its "safe" when it's cocked and ready to fire like "all firearms"