"Guy Fawkes" quote
The .220 Swift is the fastest factory round, at 4200 fps.

Nope there's another.

The .204 RUGER shares the same case head and overall length cartridge as the
..223 Remington, but uses a slender new .20 caliber, 32 grain, V-MAXTM
bullet. The .204 RUGER's bullet has an extremely efficient ballistic
coefficient of 0.192, and an amazing muzzle velocity of 4,225 feet per
second.


Low recoil, low bang, fun to shoot.