The shotgun is mounted on a bungee single point sling. It hangs freely, with the barrel slipped into a homemade holder made of extra clips and straps. I like the bungee idea for the pistol as well. I could even use an m4 mag pouch and cut a small hole in the bottom for the suppressor to slip through.
Ideally, I'd like to find something like this:
http://www.specopstactical.com/shop/...er-p-5150.html