600 Nitro Express Handgun NOTE: This guy is nuts! Pfeifer-Zeliska .600 Nitro Express Handgun "How much gun is TOO much gun?!" December 4, 2009 I have seen little handguns and I have seen big handguns, but until now I have never seen to much handgun. This is TOO MUCH HANDGUN! Forget everything you've heard about magnum revolvers; this is the ultimate. Caliber .600 Nitro Magnum - Measured by muzzle energy, it is the most powerful in the world: http://www.tonyrogers.com/weapons/pfeifer-zeliska.htm