Golly! My dad had bullet trap in our basement back in the mid-1950s and we shot .22 shorts all the time down there in an old single-shot Winchester Model .22-02 that he won as a prize out of a Cracker Jacks box way back when he was a kid. It’s where & how I learned to shoot when I was 6 years old. I’m glad we live far out in the boonies these days.
Same here. Back in the late 1950’s to mid-1960’s, my father and I had a back stop in the basement. My dad found a chunk of steel somewhere that was about 3/8” thick and about 4’ x 4’. We built a wooden frame around it. The metal was held at a 45 degree angle and there was a wooden box underneath that carried about 6” of sand.
I bought some .22 short “gallery” loads. They disintegrated when they hit the steel. There was a small shower of sparks when it hit. We also used standard velocity .22LR. They were louder, but more accurate. The sand safely stopped them. We never had any problems with the Police, but I don’t know that any of the neighbors could have heard them.
Some time later, I started shooting the .38 caliber plastic bullets/cases that were sold by Speer. They were propelled by only the primer. They were a standard item, sold at most gunshops, so someone other than us was shooting in their basement.