All of the above... and keep track of that barrel-cylinder gap and what it will do to a backpack or your own flesh if you get a bit careless.

I made a blast shield out of two pieces of elk leather glued together for double thickness, and I use it for my backpack. It gets a real good workout, but it saves the backpack. Yeah...I forgot to use it once and my good backpack sports some pretty ugly holes in it.