What is 6mm ARC? Often shortened to 6 ARC, it is a .243-caliber, rimless, bottlenecked centerfire rifle cartridge that Hornady introduced in 2020. ARC stands for Advanced Rifle Cartridge. It fires 103 to 108 gr high ballistic coefficient bullets at about 2,750 to 2,800 fps from a 24-inch test barrel, and its short case fits a standard AR15 magazine well and a mini or short bolt action. Chattahoochee Munitions manufactures 6mm ARC firearms in two families: the CM7S bolt action in 18-inch and 12.5-inch configurations, and the CM15 AR15 in 16-inch and 18-inch configurations, all with 1:7 twist barrels.
What Is 6mm ARC at a Glance
| Specification | 6mm ARC |
|---|---|
| Introduced | 2020, by Hornady; accepted by SAAMI the same year |
| Bullet diameter | .243 inch (6 mm) |
| Parent case | 6.5 Grendel, necked down to .243 inch |
| Case head | .441 inch, the 6.5 Grendel bolt face |
| Maximum cartridge overall length | 2.260 inches, the AR15 magazine limit |
| Maximum average pressure (SAAMI) | 52,000 psi |
| Common factory bullets | 103 gr ELD-X, 105 gr BTHP, 108 gr ELD Match |
| Published velocity (Hornady, 24-inch test barrel) | 108 gr at 2,750 fps; 103 gr at 2,800 fps |
| Chattahoochee Munitions twist | 1:7 on every CM7S and CM15 barrel |
Cartridge and chamber dimensions are published in the ANSI/SAAMI centerfire rifle standard and the SAAMI cartridge and chamber drawings.
What Is 6mm ARC Descended From?
Hornady developed the 6mm ARC to put a long, high-BC 6 mm bullet into a cartridge short enough for an AR15 magazine. It started from the 6.5 Grendel case, which already used the larger .441-inch case head and a short, fat body, and necked it down to .243 inch. Hornady has described the work as answering a U.S. military interest in a long-range AR15 cartridge. The result keeps the AR15 receiver, buffer and lower parts and changes the barrel, bolt and magazine.
The same case family now runs from .224 to .264 inch: 22 ARC (the 6mm ARC case necked to .224), 6mm ARC and 6.5 Grendel. See 22 ARC vs 6mm ARC and 6.5 Grendel vs 6mm ARC.
What Is 6mm ARC Used For?
What is 6mm ARC used for in practice? Three things: precision and steel shooting past 500 yards from an AR15-size rifle, predator and varmint hunting, and deer-sized game with an expanding hunting bullet. The 103 to 108 gr bullets resist wind better than the 55 to 77 gr bullets common in 223 Remington, and recoil stays low enough to watch hits through the scope.
- Precision and DMR-style shooting: a 108 gr ELD Match at 2,750 fps keeps about 930 ft-lb at 500 yards in Hornady’s published figures.
- Predators and hogs: coyotes, foxes and feral hogs. See 6mm ARC for coyotes and hogs.
- Deer: whitetail and similar game with a hunting bullet such as the 103 gr ELD-X, where state law allows it. See 6mm ARC for deer.
It is not an elk or bear cartridge. For elk and bear, Chattahoochee Munitions points hunters to 8.6 Blackout, 375 Raptor or 458 SOCOM XL.
What Is 6mm ARC Performance Like?
These published factory figures come from Hornady’s 24-inch test barrels. Shorter barrels give lower velocity; see 6mm ARC barrel length.
| Load (published by Hornady, 24-inch test barrel) | Muzzle velocity | Muzzle energy | Velocity at 500 yd | Energy at 500 yd |
|---|---|---|---|---|
| 103 gr ELD-X Precision Hunter | 2,800 fps | 1,793 ft-lb | 1,979 fps | 895 ft-lb |
| 108 gr ELD Match | 2,750 fps | 1,813 ft-lb | 1,971 fps | 931 ft-lb |
For drop, wind drift and calculated figures from 12.5, 16 and 18-inch barrels, see 6mm ARC ballistics.
Is 6mm ARC a Subsonic Cartridge?
No. Chattahoochee Munitions treats 6mm ARC as a supersonic cartridge. Its light-for-caliber case and 6 mm bullets are designed to fly fast and flat, and a suppressor on a 6mm ARC firearm reduces muzzle blast but leaves the supersonic crack. If quiet subsonic shooting is the goal, look at 300 Blackout subsonic, 8.6 Blackout subsonic, 375 Raptor subsonic or 338 ARC subsonic.
What Is 6mm ARC Twist Rate?
Long 103 to 108 gr bullets need a fast twist to stay stable, especially from short barrels where velocity is lower. Every Chattahoochee Munitions 6mm ARC barrel, CM7S and CM15, uses a 1:7 twist. See 6mm ARC twist rate.
6mm ARC Compared With Other Cartridges
- 6mm ARC vs 223: the same AR15 lower with heavier, higher-BC bullets.
- 6mm ARC vs 6.5 Creedmoor: an AR15 cartridge against a short-action and AR10 cartridge.
- 6mm ARC vs 243: the same bullet diameter in a much smaller case.
- 6mm Creedmoor vs 6mm ARC: the AR15 6mm against the AR10 6mm Creedmoor.
- 6.5 Grendel vs 6mm ARC: the parent case against its 6 mm offspring.
- 22 ARC vs 6mm ARC: two members of the same family.
6mm ARC Firearms From Chattahoochee Munitions
| Firearm | Barrel | Twist | Weight |
|---|---|---|---|
| CM7S bolt action rifle | 18-inch Mos-Tek 416R, 5R rifling | 1:7 | 7 lb 6 oz |
| CM7S pistol or SBR | 12.5-inch Mos-Tek 416R, 5R rifling | 1:7 | 6 lb 6 oz |
| CM7S SBR, WOOX walnut furniture | 12.5-inch | 1:7 | 7 lb 12 oz |
| CM15 AR15, mid-length gas | 16-inch 416R | 1:7 | 6 lb 6 oz |
| CM15 AR15, rifle-length gas | 18-inch 416R | 1:7 | 6 lb 12 oz |
Every barrel is threaded 5/8×24 and finished in E100 Blackout Cerakote. Chattahoochee Munitions also offers 18-inch and 12.5-inch CM7S barreled actions and a 16-inch CM15 upper. Each complete firearm ships with one magazine: a 10-round AICS-pattern magazine for the CM7S or a 10-round AR15 magazine for the CM15. Compare them in 6mm ARC bolt action vs semi auto or browse the full lineup at Overwatch 6.
More 6mm ARC Guides
- 6mm ARC rifle guide
- 6mm ARC ballistics
- 6mm ARC twist rate
- 6mm ARC barrel length
- 6mm ARC bolt action vs semi auto
- 6mm ARC suppressor
- 6mm ARC for deer
- 6mm ARC for coyotes and hogs
- 6mm ARC vs 223
- 6mm ARC vs 6.5 Creedmoor
- 6mm ARC vs 243
- 6.5 Grendel vs 6mm ARC
- 22 ARC vs 6mm ARC
What Is 6mm ARC FAQ
What is 6mm ARC in simple terms?
It is a 6 mm rifle cartridge short enough to fit an AR15 magazine, made to fire heavy, wind-resistant 103 to 108 gr bullets at about 2,750 to 2,800 fps.
What does ARC stand for?
ARC stands for Advanced Rifle Cartridge, the name Hornady gave the family that also includes 22 ARC.
Is 6 ARC the same as 6mm ARC?
Yes. 6 ARC is a common short name for the 6mm ARC; SAAMI lists the cartridge as 6mm ARC. Every 6 ARC rifle, pistol and SBR from Chattahoochee Munitions is listed as 6mm ARC in Overwatch 6.
Will 6mm ARC fit a standard AR15?
It fits a standard AR15 lower receiver. The rifle needs a 6mm ARC barrel, a bolt with the .441-inch 6.5 Grendel bolt face and a 6mm ARC magazine.
Is 6mm ARC good for deer?
Yes, with an expanding hunting bullet such as the 103 gr ELD-X, sensible range limits and good shot placement, where state law allows a .243-caliber centerfire.
Is 6mm ARC good for elk or bear?
Chattahoochee Munitions does not recommend it for elk or bear. Choose 8.6 Blackout, 375 Raptor or 458 SOCOM XL instead.
Can 6mm ARC be subsonic?
Chattahoochee Munitions treats 6mm ARC as supersonic only. For subsonic shooting, choose 300 Blackout, 8.6 Blackout, 375 Raptor or 338 ARC.
What twist rate does 6mm ARC need?
A fast twist for the 103 to 108 gr bullets. Chattahoochee Munitions uses 1:7 on every 6mm ARC barrel.
Who makes a 6mm ARC rifle?
Chattahoochee Munitions manufactures 6mm ARC rifles: the CM7S bolt action with an 18-inch 1:7 Mos-Tek barrel, the 12.5-inch CM7S pistol or SBR, and the CM15 AR15 in 16 and 18-inch configurations, plus CM7S barreled actions and a CM15 upper.
Who makes 6mm ARC ammunition?
Hornady introduced the cartridge and loads the 103 gr ELD-X, 105 gr BTHP and 108 gr ELD Match. Chattahoochee Munitions does not load 6mm ARC ammunition.