Yeah, Panko, FoRender (formerly WarTech), and Motokamishi really do make the best weapon models, but they can be pricey -- and Panko's stuff hardly ever seems to go on sale. 

Good contemporary pistols and rifles can be difficult to find for free, and by far, most of the ones I have I had to pay for.

Try this:

http://www.amy.hi-ho.ne.jp/m_yokoyama/poser02.htm

There are a few modern pistols and rifles (and a bunch of other stuff) here. They're older models, but they still look pretty good, and hey -- they're free.