Re: **Reloading Safety Reminder**
Was your coworkers bolt a Remington with two holes, or a Winchester? My sons Winchester has two vents like your too.
I think the number of holes behind the bolt head and locking lugs probably don't matter to strength or function at all... unless you got real carried away it might affect function, all the strength is in the bolt head itself, the body is just a carrier.
I also think that another hole or two that vented down the front of the mag well would relieve alot of pressure coming out of the forward hole, the one that puts crap back in your face. The forward hole would definately save the bottom metal from blowing off in a real serious over pressure situation, but hey, it's your face or the stock and bottom metal! You choose.
When my M14 blew up, it was "real" ugly in the mag area, that was a full casehead and lower bolthead failure though. You could stick your finger through the hole in the case at the bottom rear of it, that blew the bottom of the bolt off and down through the loaded mag, splitting the stock front AND rear, top and bottom, bending the op rod, barrel and cracking the inside of action... Lucky it vented DOWN! Springfield Armory replaced the whole barreled action for $600 too, after they magnafluxed the action and found hailine fractures in it.
I did have problems with the vent hole on a Rem 700 in 300WM, it needed to be chamfered, as it would catch on the cartridge belt and stop the bolt of the top round with all the pressure it had against it, this only happened whan the mag was full and you opened the bolt to try and chamber the top round. Chamfering the hole real good was all it needed though.