here is a video of it in action
+ YouTube Video
I decided the bullet trap needed a blast shield to reduce the amount of blast entering and to limit the amount of debris exiting. I had a couple of pieces of stainless plate laying around and made one up. I had to extend the gun rail 8" to accommodate it.
It was worth the trouble, it keeps a lot of crap from blowing out of the pipe when you are testing guns, specially ones in 7.62 x 54R