Finally getting back into it to finish up GURPS Metro: Weapons, but I'm planning an Addendum post with specific models and examples. I'm also planning a "Here's why gun control doesn't work, look at all these guns made despite total gun control. Stop being an idiot, guns have existed for 1000 years, and aren't going away no matter how hard you wish for it." post.
I've got plenty of links from The Firearm Blog for some nice compilations, but if anyone has some other links lying around to some good rough-hewn guns, that'd be fantastic for both purposes.
SMGs and Shotguns in particular, but old fashioned or improvised rifles, pistols, and anything else are good.