Looks good! Nice and beefy. Would download this mod.
I'd advise altering or removing the rebar handle sticking up in the middle - it gets quite close to the crosshair in first person, which is something we always strive to avoid. It can cause a quite messy feel in combat.
A couple style notes, if you want it to really feel like DRG:
Be careful not to have too many loops on your rounded bits. Generally, we try to stick to 6 or 8, with perhaps 10 at most if desperately needed. The faceted look is important. You are allowed to chamfer those edges though, if it feels TOO lo-poly.
And consider beefing the barrel and body up even more. Dwarf guns be chonky.