So, all these "bullet holes" in the walls....were they concentric, or were they key-holed?
There weren't "all these" bullet holes in the walls. Probably no more than 10.
As I recall, the holes were normal looking bullet holes, like the ones in the gunpowder cans.
There were also a lot of split cases flying around to. My Wife was about 30 yards away and a M1 Carbine case hit her in the face causing a crescent shaped bruise.
The cases had such force flying back wards that they put their head stamp in the ammo can metal and some cases tore through the steel cans.
Interesting that one 50 cal can that contained 7.62x39 ammo was expanded like a balloon and beat to heck but it contained all the ammo. There was not a single hole in that can.
One bullet hit my house roof, about 40 yards away.
A couple days after the fire a mark in a shingle caught my eye as I was looking for damage.
The bullet, M1 Carbine as I remember, hit the shingle on the lower edge. It cut the shingle almost in half and buried in the half inch plywood.
So, like I said, don't put all your faith in such as, "ammo is no problem in a fire because it just mildly bursts".
Up until that fire I believed the same thing.