YES! I learned the harder way about the dry/wet sand. After a few years the backstop appears to be a sand mound with just a bit of the rubber tires showing. Because of occasional down pours here we learned to drag a tarp over the top of the mound when we were done for the day. The initial construction was the real work....the maintenance after is easy.LHSmith said:36" of dry sand will stop a 50 cal. BMG with ZERO chance of ricochet. The sand must be kept dry or the depth must be doubled. .308 requires 24", and .223 requires 16" of dry sand. This data comes from a military range design document DA PAM 385-63. These amounts do not address automatic fire weapons.
spclark said:Tires aren't really a good idea anymore because of the possibility of aramid (Kevlar) or steel fabric included in their construction.
Not to say they're not still used for building backstops mind you....