The 6mm BR Norma goes by many names. Some call it the 6mm Norma BR. Some shorten the name to 6 BR Norma, or even shorter 6 BR. The headstamp on Peterson casings is 6mm BR Norma.
The 6mm BR Norma was introduced in 1996, designed for use with long, very low drag bullets. It is an excellent long-range target caliber with light recoil, which helps when your goal is to put all the bullets in the same hole at the target. The 6mm BR Norma is particularly well suited for 1,000-yard bench rest shooting. The 6mm BR is also an excellent long-range varmint caliber.
Peterson’s 6mm BRs have a small rifle primer pocket and they also have harder heads, which results in longer primer pocket life.