Daily Bulletin » Brownells 6mm ARC

6mm ARC — Efficient 6mm Cartridge That Works in AR15s

Editor — Fri, 05 Dec 2025 21:41:40 +0000

In June 2020, Hornady introduced the 6mm ARC, a new SAAMI cartridge optimized for AR-platform rifles*. The new 6mm ARC is basically a 6.5 Grendel necked down to 6mm, with the shoulder moved back around .030″. That pushed-back shoulder does reduce case capacity (and velocity), but we assume Hornady did that to create a shorter, proprietary chamber so people could not simply neck-down Lapua 6.5 Grendel brass, as has been done for years with Robert Whitley’s outstanding 6mm AR wildcat.

CLICK Image for official SAAMI Specifications:

If you are intrigued by the 6mm ARC, you’ll find the products you need at Brownells — barrels, bolts, mags and even complete 6mm ARC Rifles. Midsouth has 6mm ARC ammo and reloading dies. For general information, see 6mm ARC Wikipedia Info Page.

What Is the 6mm ARC Cartridge?
The 6mm ARC cartridge is a new SAAMI-spec cartridge based on the 6.5 Grendel case necked down for 6mm bullets, with the shoulder moved back 0.030. Yes it is designed to run in AR15-platform rifles. You’ll need a new barrel, bolt, and mags. If you already have an AR chambered in 6.5 Grendel, the ONLY thing you need to change is the barrel. Everything else — bolt, magazines, gas system – is compatible with 6mm ARC.

▶ Official SAAMI Cartridge (not wildcat)
▶ Fits standard AR15-platform rifles
▶ Fits Short/Mini action bolt rifles
▶ Efficient short, fat case design
▶ 30-degree case shoulder

For more INFO, see 6mm ARC Info Page.

What Do I Need To Shoot the 6mm ARC?
Faxon and Ballistic Advantage are already producing barrels, with more manufacturers sure to follow. All the other required components are already on the market for 6.5 Grendel rifles. Aero Precision already offers complete 6mm ARC uppers.

If you’re converting a standard 5.56×45 mm (.223 Rem) AR15 upper to shoot 6mm ARC, you’ll need a 6mm barrel, a Type II 6.5 Grendel bolt carrier group, and new magazines. Some folks have suggested standard AR mags will work, but trust us, you want the magazines that have been designed for 6.5 Grendel. Most of the hardware you need is available at Brownells.

6mm ARC Videos from Hornady (18 Total)

6mm ARC: Overview
6mm ARC: Handloading
6mm ARC Initial Offerings
6mm ARC: AR-15 vs AR-10
6mm ARC vs. 6.5 Grendel
6mm ARC vs the Creedmoors
6mm ARC: 6.5 Creedmoor of the Gas Gun World
6mm ARC vs 308 WIN
6mm ARC: How it started

6mm ARC: What is it
6mm ARC: Military Application
6mm ARC vs. 6.8 SPC
6mm ARC: Bolt Gun Application
6mm ARC: Cartridge Design
6mm ARC: Best AR-15 Cartridge
6mm ARC: Hunting
6mm ARC: Match
6mm ARC: Barrel Length

* While 6-6.5 Grendel shooters are known to run stout pressures, the new 6mm ARC cartridge has a relatively moderate Maximum Average Pressure (MAP) rating of 52,000 psi according to the official SAAMI specifications. For a variety of reasons, is wise to keep pressures in a semi-auto rifle moderate. Don’t chase the velocities you might get in a bolt-action gun.

6mm ARC — An Efficient 6mm That Runs in an AR15

Editor — Thu, 19 Dec 2024 13:51:08 +0000

CLICK Image for official SAAMI Specifications:

▶ Official SAAMI Cartridge (not wildcat)
▶ Fits standard AR15-platform rifles
▶ Fits Short/Mini action bolt rifles
▶ Efficient short, fat case design
▶ 30-degree case shoulder

For more INFO, see 6mm ARC Info Page.

6mm ARC Videos from Hornady (18 Total)

All About the 6mm ARC — Performance, Specs, Video Reviews

Editor — Tue, 19 Dec 2023 15:56:06 +0000

CLICK Image for official SAAMI Specifications:

▶ Official SAAMI Cartridge (not wildcat)
▶ Fits standard AR15-platform rifles
▶ Fits Short/Mini action bolt rifles
▶ Efficient short, fat case design
▶ 30-degree case shoulder

For more INFO, see 6mm ARC Info Page.

6mm ARC Videos from Hornady (18 Total)

6mm ARC Cartridge — SAAMI Specs, Components, Videos

Editor — Sun, 03 Jul 2022 07:52:39 +0000

CLICK Image for official SAAMI Specifications:

If you are intrigued by the 6mm ARC, you’ll find the products you need at Brownells — uppers, barrels, bolts, and magazines. Brownells also sells Hornady-made 6mm ARC factory-loaded ammo, but most varieties are out-of-stock right now, as is the 6mm ARC brass. More brass and ammo should arrive soon. Midsouth is also taking brass/ammo backorders. For general information, see 6mm ARC Info Page.

▶ Official SAAMI Cartridge (not wildcat)
▶ Fits standard AR15-platform rifles
▶ Fits Short/Mini action bolt rifles
▶ Efficient short, fat case design
▶ 30-degree case shoulder

For more INFO, see 6mm ARC Info Page.

If you’re converting a standard 5.56×45 mm (.223 Rem) AR15 upper to shoot 6mm ARC, you’ll need a 6mm barrel, a Type II 6.5 Grendel bolt carrier group, and new magazines. Some folks have suggested standard AR mags will work, but trust us, you want the magazines that have been designed for 6.5 Grendel. All the hardware you need is currently available at Brownells.

6mm ARC Videos from Hornady (18 Total)

6mm ARC Cartridge — SAAMI Specs, Build Requirements, Videos

Editor — Thu, 23 Jul 2020 19:52:13 +0000

CLICK Image for official SAAMI Specifications:

▶ Official SAAMI Cartridge (not wildcat)
▶ Fits standard AR15-platform rifles
▶ Fits Short/Mini action bolt rifles
▶ Efficient short, fat case design
▶ 30-degree case shoulder

For more INFO, see 6mm ARC Info Page.

If you’re converting a standard 5.56×45 mm (.223 Rem) AR15 upper to shoot 6mm ARC, you’ll need a 6mm barrel, a Type II 6.5 Grendel bolt carrier group, and new magazines. Some folks have suggested standard AR mags will work, but trust us, you want the magazines that have been designed for 6.5 Grendel. All the hardware you need is currently available at Brownells. And Brownells also sells complete Aero Precision 6mm ARC Uppers, starting at $749.99.