The Thompson/Center Ugalde, or TCU family of wildcat cartridges, was developed by Wes Ugalde of Fallon, Nevada, by necking up
.223 Remington
The .223 Remington (designated as the 223 Remington by the SAAMI and 223 Rem by the CIP) is a rimless, bottlenecked rifle cartridge. It was developed in 1957 by Remington Arms and Fairchild Industries for the U.S. Continental Army Command ...
brass to accept larger bullets. The cartridges were developed for the Thompson Center Arms Contender single shot pistol, and are widely used in
handgun
A handgun is a short- barrelled gun, typically a firearm, that is designed to be usable with only one hand. It is distinguished from a long gun (i.e. rifle, shotgun or machine gun, etc.), which needs to be held by both hands and also braced ...
The Contender pistol, with its break action, provides a very versatile platform for experimenting with cartridges, since all that is needed to change calibers is to change barrels. While not as strong as bolt action designs, such as the Remington XP-100, the Contender is capable of handling medium power cartridges, and many wildcats appeared based on cartridges such as the