When not actually doing sound design I do a lot of reading about it. This link was forwarded to me by Charles Maynes, one of the premier recordists of weapons for movies and games. This is the kind of stuff sound types revel in...
http://www.firearmsid.com/Feature Articles/soundofbullets/soundofbullets2.htm
http://www.firearmsid.com/Feature Articles/soundofbullets/soundofbullets2.htm