Hello everyone. Part of what i do when I shoot is study the effect of my backstop on the rounds i am shooting. I built a backstop from concrete block, with 2 inch pink house foam insulation directly in front of it to deflect bullets down to the ground if they reach the concrete and bounce back. The target stand itself is modifiable to make several layers of wood up to 9 inches thick (for the .223), as needed, before the rounds penetrate the foam and bounce off the concrete. The whole thing sits between and overlaps two large hedge trees (osage orange) for an additional nearly 6 feet of side stop beyond the 6 feet in the middle. At this time we are only shooting .22 lr and .223 here. The backstop positively stops .22 long rifle from any range 50 feet or greater without visible damage to the concrete. Today i also added several layers of pine to make a .223 target stand that positively stops those from any range 25 yards or greater. Anyway, today i spent a little time digging a few rounds out of the backstop wood and from the ground in front of the concrete. I also experimented with decreasing thicknesses of wood to see what the minimum would be for the .223 at 50 yards. Here is a photo of some of the rounds: Along the left side are four .22 long rifle rounds that were embedded in the particle board from 50 yards. These penetrated 2 1/2 to three inches of hard pine, and 3/4 or two layers of 3/4 inch soft particle board, sometimes tumbling..sometimes not...you can see the variety of expansion from the 36 gr hp bullets...these were federal bulk ammo from walmart. The bullets you see were picked out of particle board just prior to the pink foam catch barrier. I've seen nearly identical results with winchester and remington golden bullet bulk packs. The accuracy edge goes to remington for my gun (remington 581) and my wife's crickett rifle, by a wide margin. From 50 yards, nothing reaches the concrete from the .22 from any of the three brands. Along the top are 5-55gr fmj tula rounds from the .223. The two on the left penetrated 8 inches of pine and were imbedded in a 3/4 inch pine board i dug them out of...50 yards. The boards are kept loosely stacked to help bleed off bullet energy and catch the bullets...they seem to penetrate further when the boards are tight. After all, the real point to the stop is safety..nothing gets through. The three on the right were shot through only two 2x8 pieces, two 3/4 inch pieces of particle board and they penetrated the foam and landed on the ground after making a 1/2 inch depression in the concrete block nearly 3 inches across. You can see where concrete is fused with molten lead in the jackets of these rounds. I stopped doing this after getting some hollow point results against the concrete...lol. I only shot the 55 gr fmjs from 50 yards, where i shot a couple of 62gr at 25. I felt it was worth some sacrifice of the materials to get the information. Concrete block is cheap. There were no richochet rounds whatsoever. there never are with this backstop. It was interesting to me to see the hollow points behaving in a similar manner to the fmj with one exception...well two..they are 62 gr tula, and they separated from the lead with significant fragmentation in the surrounding wood. The FMJ also had some of this, but there seemed to be more lead still in the jacket in every case. There is nearly no lead in any of the hollow point rounds i found...although there is concrete fused on the one from 25 yards. I limited my shots at 25 yards due to the damage to the 4 inch thick block. I don't want to replace those any more than i have to and several more in the same spot will surely punch through. I have found that the replaceable wood layers effectively trap these rounds before they even hit the pink foam. I will continue to use the particle board and foam for the .22 lr so i can collect the lead behind the foam. also interesting to me is that the .223 55gr fmj won't spin my durasoft target at 50 yards..lol...i just goes right through and makes it shake violently then punches into the backstop...lol. The instructions specifically say 50 yards minimum for centerfire rifles....i guess it's further if you want it to spin. anyway, i thought you might find that interesting.