What can I use for an indoor backstop? I have an area at work I can set up an indoor range with a 30 yard shot with cement walls. What could I use as a backstop? Maybe I'm getting old. The days of practicing out in the snow in the winter are getting old[:-].

An old mattress would work. Or you could line the wall with a few layers of solid insulation. I use this in my basement. 3 layers of 2".

what i was going to do at my work is put a few bails of straw up and put a old blanket of top of it so that way it would help stop it better.

The solid insulation sounds like a good idea to me.