OK, here are a few crits.
1. I'd lay the shotgun down a bit. I'd make it a bit more horizontal than vertical (red and blue arrows) That way, you won't see as much of the arm as you do now.
2. The arm is at a strange angle. If you look at the arm at the moment, it's like he has two left arms. The arm should angle more to the left of the screen. To get that angle at the moment, I think you are going to have to do option one, or it's going to look really strange.
3. Reduce the spec on the arm, its a bit glossy at the moment.
As has been said before, this is the most bodaciously sexy version of the shotty yet, really great work!