The 1300 bolt head unlocks before the hammer ever gets to strike the firing pin. If you are not holding on to the forearm the bolt begins opening up and moving rearward before the slug even gets out of the shotgun shell.
So if the bolt head unlocks before the firing pin strikes, why did they make the gun to lock up at all??? Was it just to keep the shell in the chamber while one is carrying it in the field? I am NO gunsmith, but I think you exagerate what actually is happening quite a bit here. I somehow think there would have been a lot of mishaps with this gun if the bolt remained in an unlocked position before the firing pin struck or the slug even got out of the shell. It would almost be like holding a shell in your hand while someone strikes a nail against the primer. I don't think anyone would want to try anything like that, don't you?
I am not accusing gunsmiths of anything, but I do know of a number of people who had their scopes mounted by them or gun shops and I, a complete amatuer, would surely have done a better job.