A decent start, but its scale is looking wonky in places.
The barrels - and the fact it's a minigun - would imply a very solid and bulky weapon, but a the carry handle at the front looks pretty thin and small, almost too small to even fit a hand around. I can't tell if that's the rear handle at the end, either... it's kinda dainty and fragile looking if it is. And those little bipod legs don't look too useful or stable.
The scale of these also implies that the barrels are about the height and width of a full grown man... which is a little excessive :P
I think maybe you should strip it back down to where you were and then consider where to add detail that will be visible and look cool. You can see the chainguns in
Doom 3 and
UT2k3 both have a lot of of "unnecesary" details around the visible end of the weapon to make them look more interesting than just having 6 barrels on your screen.
Hmm, that rambled on a bit more than I thought it would, sorry :x