#SmallCaliberHighVelocity

In a recent Modern Personal Defense Weapon Calibers post, we discussed the .223 Timbs, a pseudo-wildcat load of the 7.62x25mm Tokarev that uses a sabot to fire a 50gr .22 caliber projectile at 2,000 feet per second or more. At the time, very little information was publicly available regarding the origin and purpose of the .223 Timbs, and what we knew at the time could just be summed up as “it was developed by Joseph Timbs and Quality Cartridge.” After the article ran, it gained the attention of none other than Joseph Timbs himself, who reached out to The Firearm Blog, and gave us the bar booth version of the story.

It has been a little while since we visited the subject of modern personal defense weapon calibers, so to start it off again we’ll be taking a look at a new high velocity round that is only a few years old: Armscor’s .22 TCM. This round was reportedly developed by Fred Craig as a high velocity caliber for the 1911 platform, and picked up by Philippine company Armscor. Originally called the “.22 Mini Mag”, the .22 TCM (Tuason-Craig Magnum, after Craig and Armscor’s president) is designed to fit inside the magazine well of a 1911 and function from .38 Super 1911 magazines. Although a pistol round, the .22 TCM is based off the .223 Remington case, shortened by about three quarters of an inch. Thanks to the thick web of its parent case, the .22 TCM is capable of handling high pressures of 40,000 PSI. A version with a shortened projectile, the .22 TCM 9R, is compatible with shorter 9mm magazines for weapons like the Glock 17.

What was the first military .22 caliber high velocity infantry rifle round ever developed? Many would name the 5.56mm round designed in the 1950s to that title, but that would be incorrect. In truth, it’s probably impossible to know for sure due to the large number of obscure and even totally forgotten experimental rounds in history, but a very interesting candidate for this title was a development of the United States Army in the last decade of the 19th Century, designed at Springfield Armory in late 1894. The round’s official name was “0.22 Inch Caliber Cartridge for Experimental Arm”, but it has subsequently been called the “.22 Krag”, or “.22 1895 Experimental” by the small circle of ammunition collectors aware of its existence.

Almost four decades before the invention of smokeless powder, the advent of the Minié ball bullet made practical the standard infantry rifle, and with it the elongated projectile. This changed the fundamental physics of infantry weapon ammunition design, allowing longer ranged weapons firing oblong, high sectional density projectiles of smaller and smaller caliber. The arrival of smokeless powder in the mid 1880s accelerated this arms race: New projectiles, clad, or “jacketed”, with a hard metal to withstand the forces of acceleration generated by a high-velocity smokeless gun, took these principles to their extreme. By the late 1880s, infantry weapon caliber had shrunk from the ~0.69″ of the roundball-firing smoothbore muskets to less than a third of an inch (~0.30″), and smaller calibers were continuing to be adopted as the arms race to the bottom accelerated.

The flight of a rifle bullet may seem to be a simple thing – it flies through the air at high speeds, steadily losing velocity and energy until it either impacts the dirt or simply falls out of the sky. In fact, though, there is a lot of complex fluid dynamics to absorb to fully understand the flight of a bullet through the air, especially as that bullet drops below Mach 1.3 (about 1,450 ft/s) and encounters the transonic flight regime. To help us understand what happens better, we’ll turn to an instructional video from the 1950s from Shell Oil; while it covers the flight of then-high-performance aircraft, not bullets, the basic principles still remain the same. I highly recommend my readers watch the video first, before reading my discussion of it: