.22 TCM

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.[1]

22TCM
From left: .22 TCM, FN 5.7×28mm, .223 Remington
Type	Pistol/Rifle
Production history
Designer	Fred Craig
Specifications
Parent case	5.56×45mm NATO
Case type	Rimless, bottleneck
Bullet diameter	0.224 in (5.70 mm)
Neck diameter	0.255 in (6.48 mm)
Shoulder diameter	0.362 in (9.19 mm)
Base diameter	0.376 in (9.55 mm)
Rim diameter	0.378 in (9.60 mm)
Rim thickness	0.045 in (1.1 mm)
Case length	1.022 in (26.0 mm)
Overall length	1.265 in (32.1 mm)
Case capacity	15.2 gr H2O
Ballistic performance
Bullet mass/type Velocity Energy 40 gr (3 g) Pointed flat nose 2,800 ft/s (850 m/s) 696 ft⋅lbf (944 J) 40 gr (3 g) Pointed flat nose 2,070 ft/s (630 m/s) 381 ft⋅lbf (517 J)
Test barrel length: 22.75" rifle (higher velocity) and 5.0" pistol (lower velocity)

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".

The .22 TCM 9R (right) uses a shorter bullet than the regular round (left).