I have to say, that pistol is DYNAMITE. I too am trying to figure out how to mount my AR on my back...it is pretty much impossible to reach, but I need to be able to hang it somewhere! I am also worried about the weight of the AR hanging on the foam torso, mine is kinda heavy. I might reinforce the torso interior with smoothcast...I don't know.
Anyway, fantastic work so far, keep it up!