6.5mm Creedmoor

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6.5mm Creedmoor
6.5 lineup.color.corrected.png
Size comparison of some 6.5mm cartridges, left to right: .264 Winchester Magnum, 6.5×55mm Swedish, 6.5×52mm Carcano, .260 Remington, 6.5mm Creedmoor, 6.5mm Grendel
Type Centerfire rifle
Place of origin United States
Production history
Designed 2007
Manufacturer Hornady
Produced 2008
Specifications
Parent case .30 TC
Case type Rimless, bottleneck
Bullet diameter .2644 in (6.72 mm)
Neck diameter .2950 in (7.49 mm)
Shoulder diameter .4620 in (11.73 mm)
Base diameter .4703 in (11.95 mm)
Rim diameter .4730 in (12.01 mm)
Rim thickness .054 in (1.4 mm)
Case length 1.920 in (48.8 mm)
Overall length 2.825 in (71.8 mm)
Case capacity 52.5 gr H2O (3.40 cm3)
Rifling twist 1-8" (203 mm)
Primer type Large rifle, Small rifle (Alpha Munitions, Lapua and Starline brass)
Maximum pressure (C.I.P.) 63,091 psi (435.00 MPa)
Maximum pressure (SAAMI) 62,000 psi (430 MPa)
Ballistic performance
Bullet weight/type Velocity Energy
120 gr (8 g) AMAX 3,020 ft/s (920 m/s) 2,430 ft·lbf (3,290 J)
143 gr (9 g) Hornady ELD-X 2,710 ft/s (830 m/s) 2,283 ft·lbf (3,095 J)
Test barrel length: 28 inch
Source(s): Hornady,[1] SAAMI,[2][3] C.I.P. [4][5]

The 6.5mm Creedmoor, designated 6.5 Creedmoor by SAAMI, 6,5 Creedmoor by the C.I.P. or 6.5 CM or 6.5 CRDMR for short, is a centerfire rifle cartridge introduced by Hornady in 2007[6] as a modification of the 6.5 Carcano and the .30 TC,[7] and is based on the .308 Winchester.[8] It was developed in partnership by Hornady Senior Ballistics Scientist Dave Emary and Dennis DeMille, VP of product development for Creedmoor Sports, hence the name. The cartridge was designed specifically for long-range target shooting,[6] although it has success in game hunting.[7] Bullet-for-bullet, the 6.5mm Creedmoor achieves a slower muzzle velocity than longer cartridges such as the 6.5-284 Norma or magnum cartridges such as the 6.5mm Remington Magnum. However, due to its overall length of 2.825 inches (71.8 mm), it is capable of chambering in short-action rifles.

Design considerations

In general, 6.5 mm (.264") bullets are known for their relatively-high sectional density[7] and ballistic coefficients, and see success in rifle competition. The 6.5mm Creedmoor was designed for target shooting at longer ranges, and as such, couples a sensible case volume (3.40 ml) to bore area (34.66 mm2/0.3466 cm2) ratio with ample space for loading relatively-long slender projectiles providing good aerodynamic efficiency and external ballistic performance for the projectile diameter.[4] For some loads, the 6.5mm Creedmoor is capable of duplicating the muzzle velocity[2] or trajectory[9] of the .300 Winchester Magnum while generating significantly-lower recoil, based on lighter projectile weight. This cartridge is designed for a bolt-face diameter of .473 inches (roughly 12 mm), conversion of a short action rifle to another caliber (such as the .22-250 Remington, .243 Winchester or .300 Savage) with similar bolt-face diameter generally requires little more than a simple barrel change, or on the Armalite-style AR-10 series, a complete upper-assembly.

Cartridge dimensions

The 6.5mm Creedmoor has 3.40 ml (52.5 grains H2O) cartridge case capacity.

400px

6.5mm Creedmoor maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm).[4]

Americans define the shoulder angle at alpha/2 = 30 degrees. The common rifling twist rate for this cartridge is 203 mm (1 in 8 in), 6 grooves, Ø lands = 6.50 mm (0.256 in), Ø grooves = 6.71 mm (0.264 in), land width = 2.29 mm (0.090 in), and the primer type is large rifle or small rifle depending on the cartridge case manufacturer.[4]

According to the official C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) rulings, 6.5mm Creedmoor can handle up to 435.00 MPa (63,091 psi) Pmax piezo pressure. In C.I.P. regulated countries, every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. In CIP-regulated areas, 6.5mm Creedmoor chambered arms are proof-tested at 543.80 MPa (78,872 psi) PE piezo pressure.[4]

The SAAMI Maximum Average Pressure (MAP) for this cartridge is 62,000 psi (427.47 MPa) piezo pressure[10]

Performance

The 6.5mm Creedmoor is a medium-power cartridge comparable to the .260 Remington and 6.5×47mm Lapua.[11] Three-hundred yard energy using 129-grain Hornady SST bullets is listed by an independent reviewer as 1,641 foot-pounds force (2,225 J).[12] For the 140 grain bullet at 2,700 feet per second (823 m/s) initial velocity, another reviewer reports an MPBR[13] for a six-inch-high target of 265 yards (242 m), and reports a manufacturer-claim of "almost 1,600 ft·lbf (2,169 J)" of retained energy at 300 yards (274 m) using a 24 inches (610 mm) barrel.[14] SAAMI test data confirms 6.5 mm Creedmoor, 15 feet (4.6 m) from muzzle, velocity of 2,940 ft/s (896 m/s) for the 129-grain bullet and 2,690 ft/s (820 m/s) for the 140-grain bullet (which compares to .300 Winchester Magnum data of 2,930 ft/s (893 m/s) for a 200-grain bullet and 2,665 ft/s (812 m/s) for a 210-grain bullet).[2] Long-range shooter Ray "RayDog" Sanchez summarized the bolt-action Tubb 2000 rifle in 6.5mm Creedmoor as "boringly accurate" at 1,000 yards (914 m). He asserted the rifle/ammunition combination he used maintained sub-MOA groups at 1,000 yards (914 m).[15]

Handloading

File:Long Bullets.jpg
The longest 140gr bullets reach the neck shoulder junction. Thanks to the relatively-long neck, it can be reloaded with long target bullets without placing the base of the bullet below the neck. This eliminates the "donut" problem seen by many cases after being reloaded over 20 times. Right to left: is a 123gr A-Max and Remington 140gr. Calipers are set to magazine length.

Handloading costs for the 6.5mm Creedmoor are roughly-equivalent to other 6.5 mm cartridges, such as the 6.5×47mm Lapua, due to the availability of Lapua small primer brass for both cartridges.[16][17] Norma makes brass for the cartridge, and Norma brass is available through several major-retailers at approximately the same cost as Lapua brass. Lapua brass for 6.5×47 lasts for about 12-to-20 reloads.[18] Starline sells brass cases with either large or small primer pockets, with small pocket brass costing slightly more.[19] After the 6.5mm Creedmoor was introduced, it was advertised as a 60,000 psi capable case.[6] However, after it was placed into production, Hornady listed it as 62,000 ps, then registered it with SAAMI as such. For this reason, many hand loaders have poor experiences reloading for it. Blown primers on the first shot at 62,000 psi are not uncommon. Early shooting articles listed the ammo as loaded to 58,000 psi[20], but later citings list it as 57,000 psi.[21] Hornady reduced the loads in its factory ammo because of complaints it was often blowing primers.[22] Lapua delivered 6.5mm Creedmoor brass at Shot show 2017,[23], and production quantities became available via major retailers in second quarter 2017. The Lapua version has a small primer pocket.[16][24] Thus, loads from a Lapua Creedmoor are not safe in another manufacturer's Creedmoor brass featuring a large primer pocket without applying proper hand-loading test for pressure first. A smaller diameter decapping rod is required to size and decap.

The 6.5mm Creedmoor as parent case

File:Creedmoors.color.corrected.png
From left: 6mm Creedmoor, 6.5mm Creedmoor, .308 Winchester

The 6mm Creedmoor is a necked-down version of the 6.5mm Creedmoor using 6 mm (.243 inch) bullets, lighter than 6.5 mm bullets with similarly-reduced recoil.[25] John Snow at Outdoor Life designed it in 2009. As of May 2018, Savage Arms offers three bolt action rifles and one semiautomatic rifle chambered in 6mm Creedmoor.[26] As of May 2018, Hornady offers 87-gr Varmint Express, 103-gr Precision Hunter and 108-gr Match ammunition in 6mm Creedmoor.[27]

Military use

In October 2017, U.S. Special Operations Command (USSOCOM) tested the performance of 7.62×51mm NATO (M118LR long-range 7.62×51mm NATO load), .260 Remington, and 6.5mm Creedmoor cartridges out of SR-25, M110A1, and Mk 20 Sniper Support Rifle (SSR) rifles. SOCOM determined 6.5 Creedmoor performed the best, doubling hit-probability at 1,000 m (1,094 yd), increasing effective range by nearly half, reducing wind drift by a third, with less recoil than 7.62×51mm NATO rounds. Tests showed the .260 Remington and 6.5mm Creedmoor cartridges were similarly accurate and reliable, and the external ballistic behavior was also very similar. The prevailing attitude is there was more room with the 6.5mm Creedmoor to develop projectiles and loads.[28][29] Because the two cartridges (7.62×51mm NATO and 6.5 mm Creedmoor) have similar dimensions, the same magazines can be used, and a rifle can be converted with just a barrel change. This led to its adoption and fielding by special operations snipers to replace the 7.62×51mm NATO cartridge in their semi-automatic sniper rifles, planned in early 2019. In response to SOCOM's adoption, Department of Homeland Security also decided to adopt the round.[30][31] U.S. Special Operations Command will convert their 7.62×51mm NATO M110 (SASS) and Mk 20 Sniper Support Rifle (SSR) rifles to 6.5 Creedmoor in 2019, a process that only requires (at minimum) a new barrel.[32] In 2018, USSOCOM announced they would roll-out 6.5 mm Creedmoor in a long-range precision rifle, and use it in a carbine and assault machine-gun.[33] At the National Defense Industry Association’s annual Special Operations Forces Industry Conference (SOFIC), beginning May 20 2019, FN unveiled a prototype of its Mk 48 Mod 2 machine gun chambered in 6.5mm Creedmoor to fill a USSOCOM requirement. American special operations forces are interested in acquiring a lightweight belt-fed "assault" machine-gun offering better range than existing weapons.[34][35]

See also

References

  1. ↑ UPDATED: 135gr to 145gr is no longer available with 2500 ft-lb Hornady's 6.5CM section Archived 2016-01-06 at the Wayback Machine older: Hornady Manufacturing Company Archived 2011-07-12 at the Wayback Machine
  2. ↑ 2.0 2.1 2.2 ANSI/SAAMI Velocity & Pressure Data: Centerfire Rifle Archived 2013-07-15 at WebCite
  3. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 6.2 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ 7.0 7.1 7.2 Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Hornady Handbook 9, p296
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ http://www.chuckhawks.com/mpbr_hunting.htm maximum point blank range
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ 16.0 16.1 Lua error in package.lua at line 80: module 'strict' not found.
  17. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  18. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  19. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  20. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  21. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  22. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  23. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  24. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  25. ↑ SAAMI Cartridge and Chamber Drawing 6mm Creedmoor
  26. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  27. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  28. ↑ USSOCOM Adopts 6.5 Creedmoor. soldiersystems.net, 23 March 2018
  29. ↑ Weapons: The Hits Just Keep On Coming. strategypage.com, 7 January 2019
  30. ↑ SOCOM snipers will ditch their bullets for this new round next year. Military Times. 8 May 2018.
  31. ↑ Homeland Security shooters are dumping .308 for this long-range round. Military Times. 7 May 2018.
  32. ↑ 6.5 Creedmoor vs .308 Winchester… No Contest,thetruthaboutguns.com, by Jeremy S., Jun 08, 2018
  33. ↑ The US Army Special Operations Command (USSOCOM) 6.5 mm Precision Intermediate Calibre, uklandpower.com, by Nicholas Drummond, October 31, 2018
  34. ↑ U.S. Special Operators Will Soon Be Using This 6.5mm "Assault" Machine Gun The gun offers better range and accuracy over smaller belt-fed squad automatic weapons, thedrive.com, by Joseph Trevithick, May 21, 2019
  35. ↑ FN MK 48 Mod 2 Machine Gun Prototype in 6.5CM Unveiled, thetruthaboutguns.com, by Woody, Jun 11, 2019


External links

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