6mm arc ammo

What Exactly Is The 6mm ARC

If you consider the evolution of the rifle, the goal has always been—and remains—to shoot with extreme precision, as far as possible, while experiencing the least recoil and influence from wind and gravity. Just look at the evolution of .30-caliber rifle cartridges; we went from the .30-30, to the .30-06, to the .300 Winchester Magnum and now to the .300 PRC. The desire to overcome the adverse effects of wind and gravity push the design of cartridges and bullets, and shooters relish every advancement no matter how minute. So, when someone argues that we don’t need a new rifle cartridge, what they’re essentially saying is that there’s nothing to be created that’ll be desirable or useful.

Well, that’s clearly not true. The enhancement of external ballistics has been the driving force behind cartridge creation since Louis-Nicolas Flobert’s 6mm parlor guns of the mid-1800s. Everyone wants to shoot harder, faster and flatter, so desire and utility clearly exist. This is particularly true of devotees of the AR-15. Both amateur and professional ballisticians have been trying to develop cartridges for that platform for a long time. Some of these cartridges, like the 300 Blackout, found great appeal. Others, like the .30 Remington AR, proved to be misunderstood. The latest attempt at extending the reach of the AR-15 is from Hornady, and it’s called the 6mm arc ammo.

According to Hornady, they identified a need for an “unnamed” Department of Defense entity and a concept cartridge was discussed. The entity showed extreme interest, so Hornady began development. Ultimately, the result of that collaboration is what’s now known as the commercially available 6mm ARC (Advanced Rifle Cartridge), which was adopted by that undisclosed government body. For what it’s worth, I’ve been fed the “secret government agency” line so many times that it means nothing to me. And, truth be told, it should mean even less to you. I don’t care if Carlos Hathcock himself divined his dream cartridge from upon high down to some engineer in the basement of Hornady; a cartridge either fills a desire and provides utility—or it doesn’t.

But, Why The 6mm ARC?
What exactly is the 6mm ARC? It’s indeed a new SAAMI (Sporting Arms and Ammunition Manufacturer’s Institute) approved cartridge. That means there exists a set of parameters and design specifications for ammunition and firearms manufacturers to follow when building ammunition or guns for it. This is critical, because for a cartridge to have any chance for commercial success it must be SAAMI approved. Otherwise, manufacturers avoid it like a Covid-infected anti. However, the 6mm ARC isn’t really as new as it might seem.

Hornady currently offers three loads for the 6mm ARC. There’s a 105-grain boat-tail hollow-point Black load, a 108-grain ELD Match load and a 103-grain ELD-X load.
Hornady currently offers three loads for the 6mm ARC. There’s a 105-grain boat-tail hollow-point Black load, a 108-grain ELD Match load and a 103-grain ELD-X load.
Along about 1975, Dr. Louis Palmisano and Ferris Pindell took the .220 Russian case, which was based on the 7.62x39mm Soviet cartridge and necked it up to 6mm (0.244 inch), and they also changed the shoulder angle to 30 degrees. The cartridge was explicitly created for benchrest shooting and, in fact, developed a winning reputation. Ironically, even though the 6mm PPC never gained SAAMI approval, it found great popularity in the benchrest competition circuit where most shooters made their own brass and loaded their own ammo. It should be noted, however, that there are several versions of the 6mm PPC. Though they’re minutely different, this is a result of a cartridge not having SAAMI approval.

While some believe the 6mm ARC is based on the 6.5 Grendel cartridge, it’s really nothing more than yet another variation of the 6mm PPC. No doubt, the 6.5 Grendel was some inspiration for the 6mm ARC project, and it could be argued the 6.5 Grendel is nothing more than a necked-up 6mm PPC. Of course, since bullet diameter is the primary distinguishing feature of any cartridge, this makes the 6mm ARC a closer relative to the 6mm PPC. Case capacity of the 6mm PPC is about 33 grains of water. Case capacity of the 6mm ARC is 34 grains. The most critical difference is that in bolt-action rifles, from which the 6mm PPC is typically fired, according to the Western Powders Handloading Guide, the 6mm PPC is loaded to pressures approaching 60,000 psi.

For the purposes of slowing extraction and extending bolt life, Hornady set the maximum average operating pressure (MAP) of the 6mm ARC at 52,000 psi. This is identical to the SAAMI MAP of the 6.5 Grendel, but 3,000 psi less than that of the .223 Remington and .224 Valkyrie. This makes perfect sense for Department of Defense applications, where extremely high round counts are expected. Soldiers and civilians want their guns to last as long as possible, and less pressure equals less wear and a longer life.