6.5mm Creedmoor

The 6.5mm Creedmoor (6.5×48 mm), 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, developed by Hornady Senior Ballistics Scientist Dave Emary in partnership with Dennis DeMille, the Vice-President of Product Development at Creedmoor Sports, hence the name. The cartridge is a necked down modification of the .30 TC.
The 6.5mm Creedmoor was designed specifically for long-range target shooting, although it has success in game hunting. 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 , 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 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.
For some loads, the 6.5mm Creedmoor is capable of duplicating the muzzle velocity or trajectory 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), making conversion of many short (or even long) action rifles of another caliber (such as the .22-250 Remington, .243 Winchester, .30-06 or .300 Savage) with similar bolt-face diameter generally requiring little more than a simple barrel change, but 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.
6.5mm Creedmoor maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm).
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 = , Ø grooves = , land width = , and the primer type is large rifle or small rifle depending on the cartridge case manufacturer.
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 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 PE piezo pressure.
The SAAMI Maximum Average Pressure (MAP) for this cartridge is piezo pressure
Performance.
The 6.5mm Creedmoor is a medium-power cartridge comparable to the .260 Remington and 6.5×47mm Lapua. Three-hundred yard energy using 129-grain Hornady SST bullets is listed by an independent reviewer as . For the 140 grain bullet at initial velocity, another reviewer reports an MPBR for a six-inch-high target of , and reports a manufacturer-claim of "almost " of retained energy at using a barrel. SAAMI test data confirms 6.5 mm Creedmoor, from muzzle, velocity of for the 129-grain bullet and for the 140-grain bullet (which compares to .300 Winchester Magnum data of for a 200-grain bullet and for a 210-grain bullet). Long-range shooter Ray "RayDog" Sanchez summarized the bolt-action Tubb 2000 rifle in 6.5mm Creedmoor as "boringly accurate" at . He asserted the rifle/ammunition combination he used maintained sub-MOA groups at .
6.5mm Creedmoor can provide sub-half-minute of angle accuracy from factory ammo.
The ability to retain velocity keeps the 6.5mm Creedmoor with 140-grain match bullets in the supersonic range out to around , while the .308 Winchester with non-ideal for long range use 168-grain match bullets has a supersonic range of about .
Handloading.
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. As of January 2020 Lapua is also manufacturing 6.5 Creedmoor brass with large rifle primers. 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. Starline sells brass cases with either large or small primer pockets, with small pocket brass costing slightly more. 
After the 6.5mm Creedmoor was introduced, it was advertised as a 60,000 psi capable case. However, after it was placed into production, Hornady listed it as 62,000 psi, 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, but later citings list it as 57,000 psi. Hornady reduced the loads in its factory ammo because of complaints it was often blowing primers. 
Lapua delivered 6.5mm Creedmoor brass at Shot show 2017, and production quantities became available via major retailers in second quarter 2017. The Lapua version has a small primer pocket. Thus, load data for small-primer brass are not interchangeable with those for large-primer brass. A smaller diameter decapping rod is required to size and decap. As of January 2020 Lapua also manufactures its brass with large rifle primers addressing concerns that some small rifle primers may not efficiently ignite the powder charge in cold weather conditions causing hang fires or misfires. Large rifle primer Lapua brass also allows the use of a standard size decapping rod.
The 6.5mm Creedmoor as parent case.
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. 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. As of May 2018, Hornady offers 87-gr Varmint Express, 103-gr Precision Hunter and 108-gr Match ammunition in 6mm Creedmoor.
The 22 Creedmoor is another even further necked-down version of the 6.5mm Creedmoor using 22 (.224 inch) bullets, lighter than 6 mm bullets with even softer recoil. It is easier to rather neck down 6mm Creedmoor brass, or fire forming .22-250 Rem. brass for it, although there are now a number of manufacturers producing brass casings for the 22 Creedmoor caliber.
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 , 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. 
As 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. U.S. Special Operations Command will convert their 7.62×51mm NATO M110 Semi-automatic Sniper rifle (SASS) and Mk 20 Sniper Support Rifle (SSR) rifles to 6.5 Creedmoor in 2019, a process that requires just a new barrel. 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. That means that the US Special Forces will use the same calibre for an assault rifle, light machine gun, and sniper rifle. That will give better penetration and terminal ballistics (because of high sectional density and retained energy), while providing longer range precision fire. 
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 in the process of acquiring a lightweight belt-fed machine-gun offering better range than existing weapons.
In November 2019, the U.S. Navy ordered 6.5mm Creedmoor conversion kits to upgrade the M110 Semi-Automatic Sniper System to the M110K1 variant.
In April 2020 the United States Department of Defense decided to replace the Mk13 .300 Winchester Magnum sniper rifle with a barrel semi-automatic AR-10 platform chambered in 6.5mm Creedmoor and ammunition for engagements from .