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.
