The 6mm TCU Pistol Cartridge
By Chuck Hawks
Like all TCU cartridges, the 6mm TCU was designed expressly for the Thompson/Center Contender single shot pistol. It was designed by Wes Ugalde at the request of Thompson/Center for the sport of steel silhouette shooting.
6mm TCU brass is created by first necking-up a .223 Remington case to accept .243" bullets (use a tapered neck expander) and then fire-forming in a Contender chambered for 6mm TCU. Presto, a 6mm TCU case results. Once the case has been formed, it is best just to neck size for subsequent reloads. Note that T/C cautions against the use of military cases as the starting point for 6mm TCU brass.
Here are the basic cartridge dimensions: .378" rim diameter, .376" head diameter, shoulder angle 40 degrees, shoulder diameter .370", neck diameter .266". The case length is 1.750" and the overall cartridge length is 2.5".
The 6mm TCU is a good varmint cartridge with the lighter 6mm bullets in the 55-70 grain range, although what advantage it might have over the parent .223 Remington for the purpose is mostly theoretical. It has been used on the smaller species of medium game with bullets such as the 85 grain Sierra and 87 grain Hornady.
The Hornady Handbook, Sixth Edition shows that 28.0 grains of AA 2460 powder will drive their 65 grain V-Max bullet at a MV of 2700 fps from the 14" barrel of a T/C pistol. This should be a pretty good varmint load.
The Hornady 87 grain BTHP bullet can be driven at a MV of 2400 fps by 25.9 grains of AA 2460 powder. If I had a compulsion to shoot a pronghorn or a Catalina goat with a 6mm TCU pistol, that is probably the load I'd try first. Both of these Hornady loads used Hornady cases and Federal 205 primers.
The 6mm TCU has just about the optimum case capacity for a 14" pistol barrel. Its moderate recoil and excellent accuracy have endeared it to aficionados of the big T/C single shot pistols.
Copyright 2006, 2013 by Chuck Hawks. All rights reserved.