The FN 5.7×28mm (designated as the 5.7×28 by the C.I.P. and FN 5.7x28mm NATO) is a small-caliber, high-velocity, smokeless powder, rebated rim, bottlenecked centerfire cartridge designed for handgun and personal defense weapon (PDW) uses manufactured by FN Herstal. It is similar in length to the .22 WMR (5.7×27mm) and to some degree similar also to the .22 Hornet or .22 K-Hornet. Unlike many new cartridges, it has no parent case; the complete package was developed from scratch by FN.
The 5.7×28mm was developed in conjunction with the FN P90 PDW and FN Five-seven pistol in response to NATO requests for a replacement for the 9×19mm Parabellum cartridge. In 2002 and 2003, NATO conducted a series of tests with the intention of standardizing a PDW cartridge as a replacement for the 9×19mm Parabellum cartridge. The tests compared the relative merits of the 5.7×28mm cartridge and the 4.6×30mm cartridge, which was created by Heckler & Koch as a competitor to the 5.7×28mm. The NATO group subsequently recommended the 5.7×28mm cartridge, citing superior performance in testing, but the German delegation objected and the standardization process was indefinitely halted.
By 2006, FN's 5.7×28mm firearms—the P90 PDW and Five-Seven pistol—were in service with military and police forces in over 40 nations throughout the world. In the United States, 5.7×28mm firearms are currently used by numerous law enforcement agencies, including the U.S. Secret Service.
In addition to being used in the FN P90 and FN Five-seven firearms, the 5.7×28mm cartridge has subsequently been used in a number of other weapons, such as the AR-57 and FN PS90 carbines. Excel Arms has developed four firearms chambered in 5.7×28mm, MasterPiece Arms offers three different firearms in 5.7×28mm., and CMMG offers several of its AR-Style Banshee firearms in 5.7x28. As of December, 2019, Ruger offers its Ruger-57 semi-automatic pistol chambered in this cartridge. January 2021 saw the announcement by Kel-Tec of the P50 handgun, which uses 50 round P90 magazines. Palmetto State Armory introduced its Rock 5.7 pistol in January 2022; it became available for purchase in May 2022.
The 5.7×28mm cartridge itself is produced in a number of varieties, two of which—the SS195LF and SS197SR—are currently offered by FN to civilian shooters.
The .22 TCM or 22TCM (.22 Tuason Craig Micromagnum) is a proprietary bottle-necked cartridge created from a 5.56 NATO cartridge developed by custom gunsmith Fred Craig and Rock Island Armory (RIA) for semi-automatic pistols and the Rock Island M22 TCM bolt-action rifle. Before the cartridge was commercialized, it was called the 22 Micro-Mag. Similar conceptually to other bottle-necked pistol cartridges such as the larger-caliber .357 SIG, the .22 TCM trades bullet mass for increased velocity and lowered recoil.
Based on the 5.56×45mm NATO case and shortened so that the shoulder is at approximately the same length as a .38 Super cartridge, the .22 TCM is somewhat longer than the ubiquitous 9×19mm Parabellum and designed to be fired from a RIA line of firearms (which also included 9mm barrel swaps) fed by Para-Ordnance-style double-column .38 Super magazines. A sub-variant, the 22 TCM 9R, with a shorter, more deeply-seated bullet, is designed for use in Glock magazines limited to standard-length 9mm cartridges. Standard factory loads are 40-grain jacketed soft hollow point, 39-grain for "9R".
Though the .22 TCM is designed to fit inside and feed from 9 mm 1911 magazines, it shares no parentage with the Parabellum—the .22 TCM’s parent case is the .223 Rem. The 9 mm and the .223 Rem. have very similar-size case heads: .394 (9 mm) and .378 (.223), but .223 Rem. cases have a thicker web, so overall they’re a little stronger. Craig shortened the .223 Rem. case, tweaked the base and rim dimensions and then necked it back down to .224 caliber, creating the dreaded bottleneck pistol cartridge reloaders fear. Then, he crammed in a proprietary 40-grain JHP bullet to limit overall cartridge length. The result is a high-pressure (40,000 psi) handgun cartridge that will work in a 1911 platform and push a 40-grain bullet to more than 2,000 fps from a 5-inch barrel.
