Have a look at the american company creating container ranges that are certified up to 50cal. They use a snail trap to catch the projectile to do away with a toxic sand trap. It's a pretty neat idea and would be a good idea in an enclosed area like an underground range.
I couldnt find the container ranges but these guys do a snail trap and have some good info
https://www.savagerangesystems.com/content?p=ranges
Bookmarks