6mm ARC

6 mm Advanced Rifle Cartridge
6 mm Advanced Rifle Cartridge
Type	Centerfire rifle
Place of origin	United States
Production history
Manufacturer	Hornady
Produced	2020-present
Specifications
Parent case	5.6×39 mm (.220 Russian), 6.5mm Grendel[1]
Case type	Rimless, bottleneck
Bullet diameter	6.18 mm (0.243 in)[2]
Neck diameter	6.96 mm (0.274 in)[2]
Shoulder diameter	10.924 mm (0.4301 in)[2]
Base diameter	11.201 mm (0.4410 in)[2]
Rim diameter	10.44 mm (0.411 in)[2]
Rim thickness	1.5 mm (0.059 in)[3]
Case length	37.85 mm (1.490 in)[2]
Overall length	57.40 mm (2.260 in)[2]
Case capacity	2.20 cm3 (34.0 gr H2O)
Rifling twist	190.5 mm (1:7.50")
Primer type	Small rifle
Maximum pressure (SAAMI)	358.53 MPa (52,000 psi)[2]
Ballistic performance
	Test barrel length: 610 mm (24 in); Source(s): [4]

The 6 mm Advanced Rifle Cartridge (ARC) (6×38mm) is a 6 mm (.243) rifle cartridge introduced in 2020 by Hornady as a low recoil, high-accuracy long range cartridge designed around the AR-15 platform. The cartridge was originally developed at the request of the United States Department of Defense,[5] but is also marketed towards hunters and competition shooters.

The cartridge makes use of 6 mm (.243) bullets which are known for their high BCs due to being relatively long and thin, which provides for less air resistance and better energy retention at longer 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.[6]

Compatability with the AR-15

Compared to a .223 Rem AR-15, a new barrel, magazine and bolt is required to convert to 6mm ARC.[7] The 6mm ARC utilizes the bolt head size as the 6.5mm Grendel, and 6.5mm Grendel AR-magazines have also been used sucessfully with the 6mm ARC.[8] 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.[9][10]

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 in the form of less 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 6 mm 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 milliliters (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.

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