If ammunition is something that you are especially interested in in the firearms world, then you probably frequently visit the websites of SAAMI and CIP. While doing a research for another article, I visited the New Cartridge & Chamber Drawings page of SAAMI website and bumped into a new SAAMI accepted cartridge called 6mm Advanced Rifle Cartridge (6mm ARC). To my knowledge, by the time of writing this article, no company has announced this cartridge yet. Possibly, we’ll see it officially released in the near future. Meanwhile, let’s examine the 6mm ARC SAAMI drawing and see what kind of cartridge this is.The 6mm ARC is a rimless .243 caliber cartridge. Judging by the case head dimensions and the Maximum Average Pressure (MAP) of 52,000 psi, it is based on the .220 Russian case (like the 6.5 Grendel or 6mm PPC). At first glance, the 30-degree shoulder angle and the shoulder diameter of .4301″ may make you think that 6mm ARC is a necked down 6.5 Grendel, however, the length to shoulder is 1.1207″ which is shorter than 6.5 Grendel’s 1.1507″ (and longer than 6mm PPC’s 1.075″).
The maximum cartridge overall length of 2.26″ (57.4mm) is identical to the max COAL of .223 Remington which means 6mm ARC is designed to be an AR cartridge. The case length of 1.49″ results in a lot of bullet space (.77″ or 3.16 calibers) which will allow loading projectiles with very long ogives and great external ballistic performance. The SAAMI drawing states a muzzle velocity of 2,700 fps for 108-grain bullets.
243 caliber cartridges based on the .220 Russian case have been successfully used by competition shooters with the most popular of them probably being the 6mm PPC. There are several variations of 6mm PPC in the CIP standards, however, oddly enough, neither 6mm PPC nor any of its siblings are standardized by SAAMI. That being said, the 6mm ARC looks like an attempt to have a SAAMI standard cartridge of this very successful case and caliber combination.
We’ll be following the developments around this new cartridge and will write a followup article whenever it is officially announced. Stay tuned!