6 x 45 mm Load Data

Caliber Overview

The 6×45 mm, often referred to as 6 mm/.223 Remington, is a wildcat rifle cartridge created by necking up the standard .223 Remington case to accept 6 mm (.243″) bullets. It was developed to combine the efficiency and availability of the .223 Remington case with the improved ballistic performance and bullet selection of the 6 mm caliber. Because it is a wildcat cartridge, it has not been standardized by SAAMI or CIP, but it is widely used by handloaders.

The 6×45 mm is valued for its excellent efficiency, mild recoil, and versatility. It performs particularly well with lighter to medium-weight 6 mm bullets, making it suitable for varmint hunting, predator control, and light deer hunting where legal. Typical bullet weights range from about 55 to 85 grains, delivering good accuracy and flat trajectories at moderate velocities.

One of the cartridge’s main advantages is its simplicity: it can be formed easily from .223 Remington brass, requires no special bolt face, and works reliably in standard .223-length actions and AR-15 platforms. Compared to larger 6 mm cartridges, it offers lower powder consumption and reduced barrel wear.