Five gallon bucket of sand for me. Stick a hunk of innertube on the inside where bullets will impact, just to keep the sand from leaking. Tape your target to the same side. Nothing fancy, but it sure works. Tried firing a 30-06 ball round into it from 25 yards, and it didn't penetrate. Since we live on the ocean, sand is easy to get. Guys away from the beach report equal happiness filling a box with the gardener's mulch made from shredded tires. Here are some pics of my redneck setup. No reason to change a thing in the "design," and I've been doing it for close to 20 years.