MODERNIZING THE 6MM-06

New Powders and Bullets Make It Sing

- John Barsness

While many handloaders claim to be weary of amazing new 6.5mm rounds, about as many new 6mm cartridges have appeared since 2000. These newer 6mms have faster rifling twists to stabilize heavier, high-ballistic coefficient bullets, but 6mms with faster twists and heavier bullets did not suddenly appear during the past 20 years. In fact, America’s earliest 6mm featured a 1:8 rifling twist, because the original bullet tested during the 6mm Lee Navy’s development in the mid-1890s was a 135-grain roundnose. Why? For the same reason most other early smokeless military cartridges used heavy, round-nosed bullets: The black-powder cartridges they replaced used heavy, blunt bullets.

Several other 6mm rounds soon appeared, primarily designed for hunting, including the 6x57 Mauser – the 7x57 necked down and almost identical to the .244 Remington, which appeared in 1955, the same year as the .243 Winchester. However, the .244’s factory “deer” bullet weighed 90 grains due to the 1:12 twist in the Model 722 rifle and the 6x57’s factory bullet weighed 123 grains.