BrickArms Weapons Mod Gallery 2
Here are some more BrickArms weapons mods.

My son really wanted a heavy weapon, so I took the butt stock from the new SW Heavy Blaster, an M47 Tactical Shotgun, and the receiver and forward stock of an M41A Pulse Rifle and created this heavy weapon. The individual sections are all pinned together with a barrel of a spare Precision Sniper Rifle, and the scope is glued on.
The painted M41A is painted with Krylon Camo green paint - with a Q-tip. Yes, I know, I am lazy and couldn't find a micro-bristle-brush. I just sprayed the paint into the cap and dipped the Q-tip into it.
The Halo M7 SMG is a pair of clipped-down (modified) M23s with a Precision Sniper Rifle barrel running through them to pin them together. That's it. Pretty easy, huh?
Thompson 1928 (Tommy Gun) is a modified M1A1 with a M1911 forward grip pinned underneath the forward stock. It also has the drum from the horribly ugly LEGO® Tommy Gun. It, too, is pinned to the M1A1 frame. Once again, no glue, no paint.
The last Heavy Weapon mod, is a combination of the M41A Pulse Rifle, the forward stock and barrel of the M1A1 SMG mounted underneath the original grenade launcher, and finally, the receiver, scope, and barrel with suppressor of the M23 SOCOM.