And that shmexy AR2?
lol sure :3
Edit, i'd prolly have to do a video for that, I'd also need some stuff for that vid (more things to make it) Just because it involves a lot of cutting and gluing and such.
I can give you a blunt idea though.
Get a star wars SNIPER blaster

Shave off all of the scope, don't leave a stud like you do with the SMG.
Glue on a second barral right by the trigger, you can find another barrel by either cutting it off of a different gun, or get a stick and shave it down right, or something. But make sure the second barrel is a little bit shorter than the top one.
Then you get a pair of lego goggles

And either paint those black, or find black ones (i had to paint mine).
glue the goggles over the 2 barrels (glue it in the area behind where the gap behind the two barrels starts)
Gluing the goggles can be tricky, I had to cut into my goggles a little to keep them laying flat on the gun
And for a final touch, it's not needed, but it does add a lot as far as playablity goes. Shave a corner into the arm rest part, if you dont' do this, the gun won't rest nice on your minifg's arm. Lego is a mighty cigarette for not making this gun sit on a lego figs arm nicely like it should.