Bullet Trap Backstop

[Cesure]

I'm thinking of building a bullet trap out of everyday A36 plate steel angled from the vertical toward the shooter at 45 degrees. How thick would it have to be to tolerate 10mm, .45 Auto, and .44 Magnum for thousands and thousands of hits? If the frame that holds the plate lets it move some, will that make it last longer? The weight difference between 3/8" and 1/2" could be important here.

[DaleA]

Can we assume, just to be on the safe side, that you want it to handle everything up to and including full metal jacketed 'hot' loads like those from the Buffalo Bore folk?

[g.willikers]

It kind of depends on the mount.
If the targets are free to swing backwards when hit, (preferably deflecting rounds toward the ground), they generally don't have to be as thick.
Mine are 3/8" - 8" dia - and hold up quite well to .45ACP and normal pistol .44M.
They hang below an axle and spin when hit solidly.
If your backstop was free at the bottom to swing backwards, that would definitely help.
As long as it didn't twist sideways and cause ricochets.

[Cesure]

Can we assume, just to be on the safe side, that you want it to handle everything up to and including full metal jacketed 'hot' loads like those from the Buffalo Bore folk?

Yes, I can't imagine having a reason to be shooting anything harder, heavier and hotter than that. To have a backstop 30" tall and 24" wide when tilted at a 45 degree angle it would be about 42" X 24" and have a tail angled straight down to send the bullets into sand.