Wikipedia

6mm ARC

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

6 mm Advanced Rifle Cartridge
TypeCenterfire rifle
Place of originUnited States
Production history
ManufacturerHornady
Produced2020-present
Specifications
Parent case.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)[citation needed]
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]

Compatibility with the AR-15

For an ordinary AR-15 rifle chambered for the .223 Rem/5.56mm NATO, a new barrel, magazine and bolt are required to convert to the 6mm ARC.[5] The 6mm ARC utilizes the same bolt head size as the 6.5mm Grendel, and 6.5mm Grendel-compatible AR-pattern box magazines have also been used successfully with the 6mm ARC.[6] The 6mm ARC therefore can also be a suitable chambering for shorter "mini-action" bolt-action rifles.[citation needed]

Several firearm manufacturers have announced that they will be offering factory rifles chambered in the 6mm ARC.[7][8]

Diagram

File:6mm-Advanced-Rifle-Cartridge-6mm-ARC.png

Performance

The 6mm ARC is a medium-power cartridge comparable to the 6.5mm Grendel, but with better ballistics thanks to the greater muzzle velocity achieved by using lighter 6mm bullets and enough power to make use of the heavy 6mm bullets. Some have stated that it offers comparable ballistics to larger 6mm cartridges like the 6mm Creedmoor and .243 Winchester, but out of a smaller cartridge, however this simply is not true when comparing muzzle velocities between them.[9] What the 6mm ARC does offer though, is almost comparable velocities and ballistic performance, but out of a compact cartridge that has lower felt recoil and fits in the standard AR-15 length actions.

In addition to the above comments, there is some confusion with regards to the 6 mm ARC’s performance. This is because loading data given in some manuals, the 11th Edition Hornady Reloading Manual[10] for example, has two sets of data. The first set of data is loaded to the SAAMI MAP (Maximum Average Pressure) of 52,000 PSI, which is stated to be suitable for gas-operated firearms, such as the AR-15 platform and its derivatives. The second set of data is loaded to a MAP of 62,000 PSI, which is stated to be for use with bolt action guns, such as the CZ 527. The Hornady manual states that this second set of data should not be used in gas-guns. Due to the lower MAP, the performance of 6 mm ARC ammunition loaded to gas-gun pressures will, on average, be less than firearms loaded to bolt action pressures when using the same barrel length. When using shorter barrels, which are common on gas-guns, the difference will be even more pronounced.

For example, the data in the Hornady 11th Edition Manual for an 18" (457 mm)-barrelled AR-15 platform firearm was on average 200-300 ft/s (60-90 m/s) less than the data for the 24" (610 mm)-barrelled CZ 527 bolt action rifle.

An additional likely performance handicap, applicable to any magazine-fed firearm, will be to the maximum round length that can be used in its magazine. A shorter maximum cartridge overall length (COAL) lowers powder capacity, and hence potential performance, due to the bullet’s parasitic intrusion into the case. Due to the length of the heavy bullets the 6 mm ARC is designed to use and its limited COAL, this is an issue unless over-length rounds are single-fed.

See also

References

  1. ^ Hornady 6mm ARC Cartridge - What You Need to Know
  2. ^ a b c d e f g h 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. ^ Hornady's NEW 6mm ARC & Odin Work's Barrels - www.gunsamerica.com
  6. ^ gununiversity.com | 6mm ARC Released / Hands-On Testing and Comparisons, by Ryan Cleckner 3 June 2020
  7. ^ “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
  8. ^ CMMG Announces New Rifles Chambered in 6mm ARC
  9. ^ "6mm ARC vs 6mm Creedmoor". loaddevelopment.com.
  10. ^ Hornady 11th Edition Reloading Manual
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