Firearm manufacturers tend to be a lot more litigious when a name is attached instead of just a visual representation. Also a lot of the most commonly represented weapons are popular pattern firearms with tons of knock-off versions/variations. E.g. the M1911, Hi-Power, AK-47, etc. So even if something looks like an M1911, it would be hard to prove it's "really" an M1911 (no dude, it's totally a double-stack 10mm!), much less a Colt/Kimber/Springfield/Wesson blah, blah.
Hey, I hope you didn't think I'm bashing you guys about this, I perfectly understand the need and the solution - and looking at the names you have for the guns... a lot of them are better than the originals