Just a few weapons I did in my very short short free time. Most of them are very low poly. For no particular project, just my own free time.
Ak-74 with GP 30 grenade launcher, and KOBRA red dot.
M249 SAW 1800 polys
M4 2000 polys
PKM 2400 polys
Russian RPG-7D paratrooper version with Chinese scope
And a family of low poly weapons I did long time ago.