The 5.7x28mm “Cop Killer” Cartridge Myth

As a U.S. Government intelligence manager, information pills I receive a significant number of “Officer Safety” alerts generated by a wide variety of local, drug state and federal law enforcement agencies. One alert that regularly rears its ugly head focuses on the alleged “cop killer” 5.7x28mm round fired by the Five-seveN pistol manufactured by Fabrique Nationale de Herstal (FNH) of Belgium. Given my innate curiosity, medical I decided to research this super duper cop-killing round and try to put it into perspective.

This is a .224 caliber rimless, bottlenecked, boxer primed, centerfire cartridge designed for use in semi-automatic arms. (Primarily pistols and sub-machineguns.) The cartridge overall length is 1.594 inches and it can be loaded to a maximum pressure of 50,040 psi.

Published reports indicate that as factory loaded the 5.7x28mm drives a 32 grain bullet, load #SS190-AP (armor piercing), at a muzzle velocity (MV) of 2350 fps with 390 ft. lbs. of muzzle energy (ME). The 28 grain spitzer bullet, load #SS195LF-JHP, has a muzzle velocity of 2350 fps and muzzle energy of 290 ft. lbs. The 40 grain Hornady V-Max bullet, load #SS197SR, claims a muzzle velocity of 1950 fps with 340 ft. lbs. of muzzle energy. Readers old enough to remember the obsolete .22 Remington Jet small game and varmint cartridge of 1960–40 grain bullet at about 2000 fps from a S&W Model 53 revolver–will be startled to hear that the slightly less powerful 5.7x28mm is a “cop-killer” round.

It is important to remember that the 5.7x28mm velocity and energy figures were derived from a 10.35 inch (sub-machinegun length) test barrel and that the Five-seveN pistol barrel actually measures 4.82 inches in length. Realistically, we can anticipate a substantial velocity loss of about 20% when the 5.7x28mm cartridge is fired from a pistol. This would mean an actual MV of approximately 1560 fps and ME of 216 ft. lbs. for the 5.7x28mm 40 grain bullet when fired from a handgun. Because it starts a heavier bullet at lower velocity, which maximizes energy and minimizes velocity loss, this should be the most effective load for a 5.7x28mm pistol.

A comparison of the performance of the .22 Winchester Magnum Rimfire (WMR), introduced in 1959, and the 5.7x28mm is interesting. The .22 WMR shares the same bullet diameter (.224″) as the 5.7x28mm cartridge and their muzzle and energy figures are actually rather similar.-[source]