You can unwrap them in Gmax too. The poly count of that green gun is out of hand. You could probably trim some of the details off that you would never see, like the rounded end of the barrel, the trigger, those little wires, etc. You should be able to get similiar amount of detail and form around 400 polys.
You also might want to rework some of the cylinder sections where they intersect. Right now it looks like you shift scaled and extruded them essentially doubling the poly count of that section. For an example, the beginning of the barrel and the scope area. The butt of the gun looks about 60 polys when it could be under 20.
Think of it this way, an average Q3 player model is 800 polys. Your gun is 1300+ , you have 5 guys running around with those on screen and now you are drawing 10,000+ polys. The irony is that more than half of those polys are taking up the smallest percentage of the screen in form of the guns.