They look super to me, although lacking textures. The top part of the G36 (long flat piece with series of "teeth") seems pretty high poly, and you could put this detail in the texture.
However, perhaps i'm a bit out of touch and games use more polys now than they used to- i guess in fps games, the gun is the "main character", and can use a lot of polys, especially on the top/side i suppose. Is it the done thing to make a low poly version for the enemy soldiers and for low graphics settings?
Anyway they look pretty accurate to me, but i don't know an awful lot about guns.