The 6mm TCU (Thompson/Center Ugalde) is a wildcat cartridge developed by Wes Ugalde in the early 1980s. It's formed by necking down the .223 Remington case to accept a 6mm bullet, enhancing its performance for varmint and target shooting. The cartridge offers improved ballistics over the parent .223 Remington, especially in terms of velocity and energy due to the higher ballistic coefficient of the 6mm bullets.
It is predominantly used in single-shot pistols, like the Thompson/Center Contender, and has found favor among silhouette shooters for its flat trajectory and moderate recoil. The 6mm TCU is handloaded, often with bullets weighing between 55 and 95 grains. This versatile cartridge is effective for small to medium-sized game and excels in precision rifle competitions due to its accuracy.
Overall, the 6mm TCU balances high performance with manageability, making it a popular choice among enthusiasts who handload their own ammunition.