The .22 Eargesplitten Loudenboomer was designed to hit 5000 fps (3400mph), but testing the round most people agreed it only hit 4600 (Just a few dozen mph shy of glass). With modern propellants it would probably beat the glass.
> This humorously named cartridge was developed in the 1960s by P.O. Ackley for Bob Hutton of Guns & Ammo magazine, and was intended solely to exceed 5,000 ft/s (1,500 m/s) muzzle velocity. Ackley's loads only managed 4,600 ft/s (1,400 m/s)(Mach 4.2), firing a 50-grain (3.2 g) bullet. Based on a .378 Weatherby Magnum case, the case is impractically over-capacity for the bore diameter, and so the cartridge remains a curiosity. The advent of new slower-burning smokeless powders may have changed the equation.
Oh wow, this is cool. I'd never heard of this round before. I imagine you'd need a very large barrel to burn up all that powder before the bullet left the chamber.
