Real World Guns A list of the real world counterparts the "snap on, stay on" accessories are based on.
World.Guns.ru - The modern firearms and ammunition site. A site run by Max R. Popenker, a Russian gun enthusiast. Very thourough and detailed reviews and histories of personal firearms of the 20th century. Includes pistols, rifles, assault rifles, machineguns, shotguns, submachineguns and grenade launchers.
Security Arms Not much specific weapon information (i.e. mechanics, history, etc) but an amazing visual reference of 20th century firearms. Over 3000 pictures of different weapons and their variants.
Genitron (from the site description) This website is provided as a reference resource for handguns and and handgun related issues. Along with links to various firearms related information and organization websites there are links to a Handgun Reference Search Database. This database contains handgun descriptions, technical specifications, pricing and links to manufacturers and importers.
HKpro (from the site description) HKPRO.COM is dedicated to being and remaining the ultimate unofficial resource for the serious student of Heckler & Koch, and the engineering genius behind the most advanced family of tactical firearms on Earth.