Great idea. How thick is your mat of seal. I've used duct seal years ago when I was handloading pistol rounds. We would use it to test bullet expansion. I knew a guy that had a gun range in his basement. That man had a tolerant wife. We used to shoot everything from 22 LR to 44 Mag.
I think he used it as part of his back stop for small caliber rounds. 22 shorts. Thanks.