6mm ARC

The 6 mm Advanced Rifle Cartridge (ARC) (6×38mm) is a 6mm caliber (.243) rifle cartridge introduced by Hornady in 2020 as a low-recoil, high-accuracy long-range cartridge designed around the AR-15 platform.

6 mm Advanced Rifle Cartridge
TypeCenterfire rifle
Place of originUnited States
Production history
ManufacturerHornady
Produced2020-present
Specifications
Parent case5.6×39 mm (.220 Russian), 6.5mm Grendel[1]
Case typeRimless, bottleneck
Bullet diameter6.18 mm (0.243 in)[2]
Neck diameter6.96 mm (0.274 in)[2]
Shoulder diameter10.924 mm (0.4301 in)[2]
Base diameter11.201 mm (0.4410 in)[2]
Rim diameter10.44mm* (0.4410 in)
Rim thickness1.5 mm (0.059 in)[3]
Case length37.85 mm (1.490 in)[2]
Overall length57.40 mm (2.260 in)[2]
Case capacity2.20 cm3 (34.0 gr H2O)
Rifling twist190.5 mm (1:7.50")
Primer typeSmall rifle
Maximum pressure (SAAMI)358.53 MPa (52,000 psi)[2]
Ballistic performance
Bullet mass/type Velocity Energy
6.67 g (103 gr) ELD-X Precision Hunter 853.44 m/s (2,800.0 ft/s) 2,429 J (1,792 ft⋅lbf)
6.80 g (105 gr) BTHP BLACK 838.2 m/s (2,750 ft/s) 2,388 J (1,761 ft⋅lbf)
7.00 g (108 gr) ELD Match 838.2 m/s (2,750 ft/s) 2,459 J (1,814 ft⋅lbf)
Test barrel length: 610 mm (24 in)
Source(s): [4]

The cartridge makes use of 6 mm (.243) bullets which are known for their high ballistic coefficients due to being relatively long and thin, which provides for less drag and better energy retention at extended ranges. With the release in 2020, Hornady also launched three factory loads with 103, 105 and 108 gr (6.7, 6.8 and 7.0 g) bullet weights and advertised G1 ballistic coefficients of .512, .530 and .536 respectively.[5]

Compatibility with the AR-15

For an ordinary AR-15 chambered for the .223 Rem/5.56mm NATO, a new barrel, magazine and bolt are required to convert to the 6mm ARC.[6] The 6mm ARC utilizes the same bolt head size as the 6.5mm Grendel, and 6.5mm Grendel AR-magazines have also been used successfully with the 6mm ARC.[7] The 6mm ARC can also be a suitable chambering for shorter "mini-action" bolt action rifles.

Several firearm manufacturers have announced that they will be offering factory rifles chambered in the 6mm ARC.[8][9]

Comparison with other cartridges

Compared to .223 Remington

Compared to .223 Remington/5.56×45mm NATO, the 6mm ARC has more recoil and heavier ammunition, but better long-range performance with less ballistic drop and wind drift, and more retained energy downrange.

Compared to .308 Winchester

Compared to .308 Winchester/7.62×51mm NATO, the 6mm ARC has less recoil, better long-range performance in most cases in the form of less wind drift, better penetration in most cases and lighter ammunition. While the 6mm ARC has less muzzle energy, it can in some cases retain more of its energy downrange due to better ballistic coefficients.

Compared to other 6mm cartridges

The 6mm ARC is a factory cartridge which has many similarities with the 6mm AR wildcat cartridge. The case volume of the 6mm ARC is about 2.20 mL (34 grains of water), and the volume therefore lies between those of the two popular 6 mm benchrest cartridges 6mm PPC of 2.10 ml (32 grains of water) and 6mm BR of 2.50 ml (38.5 grains of water). However, the 6mm AR and 6mm ARC separate themselves from the mentioned benchrest cartridges in that they were designed with a 30-degree shoulder angle to ensure reliable feeding in an AR-15 rifle.

Larger-sized AR-10 performance cartridges such as 6XC, 6×47mm Lapua, 6.5×47mm Lapua, 6mm Creedmoor and 6.5mm Creedmoor have better long range performance compared to the 6mm ARC, but have more recoil, as well as overall lengths that make them unable to fit in an AR-15 sized magazine well.

See also

References
  1. Hornady 6mm ARC Cartridge - What You Need to Know
  2. Public Introduction - 6.5 Creedmoor - 6mm-ARC-Public-Introduction-Rev-2020-06-18.pdf
  3. Hornady 6mm ARC Cartridge - What You Need to Know
  4. 6mm ARC - Hornady Manufacturing, Inc
  5. Brand new rifle caliber: 6 mm ARC, Hornady's Advanced Rifle Cartridge! | all4shooters
  6. Hornady's NEW 6mm ARC & Odin Work's Barrels - www.gunsamerica.com
  7. gununiversity.com | 6mm ARC Released / Hands-On Testing and Comparisons, by Ryan Cleckner 3 June 2020
  8. “With the announcement of the Hornady 6mm ARC cartridge, an incredible 22 companies plan rifles for the consumer market, with more on the way.” – Tactical Life Gun Magazine: Gun News and Gun Reviews
  9. CMMG Announces New Rifles Chambered in 6mm ARC
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