A thought on the wad-cutter or semi-wad-cutter bullets... I envision the lids getting holes punched out far more often than the bullets you used in your pictures. I could be wrong but I'd like to know how it works out when you try them.
Indeed they do! I have recently started shooting the RCBS Hogdgon "skirmisher" bullet in my muskets:
It has a pretty harsh shoulder on it designed to punch clean holes in paper, and it does. It is
harder on the bucket cover. But you can just slap some duct tape over the damage and keep shooting. One cover should last at least 2 shooting sessions, and new covers are like $1.50 from Home Depot.
However, when shooting round or conical balls out of a BP revolver, the lid is darn-near self healing!
Instead of steel in bottom of the bucket, I like the mud flap idea. I wonder if they are tough enough to stop as reliably as the steel. Maybe multiple layers?
I'm just worried my range officer will assume steel means ricochets and reject it. He barely approved my steel dueling tree.
Well, the steel is hidden in the bottom of the bucket, so hopefully no one will notice!
You will probably get away with a sheet of 3/4" plywood and some rubber sheeting for handguns. I found most of my 1858 remmy balls about half-way into the bucket - they never even made it to the back with 20 grains of powder.
With my muskets, though, they will quickly shoot a "tunnel" into the mulch, and they definitely impact the steel - see the pictures in the link above. And it packs enough of a wallop to put pretty good dents in the steel.
On bucket targets; how about spray paint flat black, then spray paint a target stencil in white instead of paper and staples?
You could, but the lid gets beat up pretty quick, and you can't put up a new target if you want to check the difference between one course of fire and the next like you can with paper. But if you are just looking for something to shoot at, sure, paint it, or just get some of those stick-on orange dots and slap them on there. Or just make a red "X" with some duct tape.
I just staple a target to it.