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|.375 Ruger (9.5×65.5mm)|
|Place of origin||USA|
|Case type||Rimless, bottleneck|
|Bullet diameter||.375 in (9.5 mm)|
|Neck diameter||.405 in (10.3 mm)|
|Shoulder diameter||.515 in (13.1 mm)|
|Base diameter||.532 in (13.5 mm)|
|Rim diameter||.532 in (13.5 mm)|
|Rim thickness||.050 in (1.3 mm)|
|Case length||2.580 in (65.5 mm)|
|Overall length||3.340 in (84.8 mm)|
|Case capacity||99.0 gr H2O (6.42 cm3)|
|Rifling twist||1-12" (304.8 mm)|
|Primer type||Large rifle|
|Maximum pressure (SAAMI)||62,000 psi (430 MPa)|
|Maximum pressure (CIP)||62,004 psi (427.50 MPa)|
|Test barrel length: 23|
The .375 Ruger (9.5×65.5mm) is a rimless, standard-length rifle cartridge designed for the hunting of large dangerous game. It is designed to provide an increase in performance over the .375 H&H cartridge, yet to be chambered in a standard length action rifle. The cartridge was designed in partnership, by Hornady and Ruger. In 2007, it was released commercially and chambered in the Ruger Hawkeye African and the Ruger Hawkeye Alaskan rifles.
Like the .376 Steyr that originates from the 9.3×64mm Brenneke and the .375 Dakota proprietary cartridge that originates from the .404 Jeffery, the .375 Ruger was designed to compete with the .375 H&H Magnum, yet have the advantage of having a rimless, beltless case and can function through a standard-length bolt action rifle due to a shorter overall length.
The .375 Ruger uses a unique cartridge case designed by Hornady and Ruger. The case is of a rimless design having the base and rim diameter of .532 in (13.5 mm) which is the same diameter of the belt on belted magnum cases based on the .300 H&H Magnum and .375 H&H Magnum. This allows the cartridge to have a greater case capacity than a belted magnum case given cases of equal length. As Ruger intended the cartridge to be chambered in standard length bolt-action rifles the case length was kept to 2.580 in (65.5 mm) which is only .04 in (1.0 mm) longer than the .270 Winchester case. The maximum overall length of the cartridge is 3.340 in (84.8 mm) which is similar to the maximum overall length to standard length cartridges such as the .338 Winchester Magnum or the .30-06 Springfield. Unlike Remington Ultra Magnum cartridges, the Ruger Magnums can be chambered in standard length bolt-action rifles. This allowed Ruger to chamber the cartridge without extensively redesigning their M77 rifle to adopt them to the new Ruger cartridge.
While the .375 H&H Magnum is longer than the .375 Ruger, the latter cartridge has a greater case capacity than the Holland & Holland cartridge. This is due to the .375 H&H Magnum having a long tapered body while the .375 Ruger follows modern cartridge designs in that it has very little taper and a sharper shoulder. The case capacity of the .375 Ruger is 99 gr. of water (6.42 cm3) while the .375 H&H Magnum has a case capacity of 95 gr. of water (6.16 cm3), an increase of 4%.
Cartridge standards for the .375 Ruger were issued by SAAMI in June 2007. SAAMI recommends a 6 groove barrel having a bore Ø of .366 in (9.3 mm) and a groove Ø of .376 in (9.6 mm) with a groove width of .115 in (2.9 mm). The recommended rate of twist is one revolution in 12 in (304.8 mm). Recommended maximum pressure for the cartridge is 62,000 psi (4,300 bar).
Currently Hornady and Double Tap manufacture ammunition for the .375 Ruger cartridge. The Hornady superformance ammunition drives a 270 gr (17 g) SP-RP bullet at 2,840 ft/s (870 m/s) and the 300 gr (19 g) DGS and DGX bullets at 2,660 ft/s (810 m/s). The Double Tap achieves 2,825 ft/s (861 m/s) and 4,700 ft⋅lb (6,400 J) with a 270 grain Barnes TSX from a 23" barrel Ruger 77 African. The .375 Ruger's slightly greater case capacity, and the "short fat" cartridge efficiency lead to increases in the neighborhood of 150 fps over the H&H cartridge. Their capabilities remain essentially comparable. Since 2015 O.F. Mossberg & Sons produced bolt-action rifles of the ″Patriot″ series chambered in .375 Ruger with different stock options.
The .375 Ruger cartridge has functioned as the parent case for the 300 Precision Rifle Cartridge (300 PRC), which is essentially a necked-down version of the .375 Ruger. The American ammunition manufacturer Hornady got the 300 Precision Rifle Cartridge SAAMI-standardized in 2018. In 2019 it got C.I.P.-standardized as the 300 PRC. The 300 Precision Rifle Cartridge cartridge case capacity is 6.2 ml (95.5 grains) H2O. The .375 Ruger cartridge case was used by Hornady as the basis for a new extra long range cartridge since it had the capability to operate with high chamber pressures which, combined with a neck and barrel throat optimized for loading relatively long and heavy .308 diameter very-low-drag bullets without the need to seat the bullets deeply recessed into the case result in adequate muzzle velocities from magnum sized bolt action rifles. Rifles chambered for the 300 Precision Rifle Cartridge must be capable of handling 3.70 in (93.98 mm) overall length cartridges.
The .300 Ruger Compact Magnum or .300 RCM was designed in 2007 and uses a case designed by Hornady and Ruger based on the .375 Ruger cartridge. The case is of a rimless design having the base and rim diameter of .532 in (13.5 mm) which is the same diameter of the belt on belted magnum cases based on the .300 H&H Magnum and .375 H&H Magnum. This allows the cartridge to have a greater case capacity than a belted magnum case given cases of equal length. As Ruger intended the cartridge to be chambered in short length bolt-action rifles the case length was shortened to 2.10 in (53 mm) which is similar to the .308 Winchester case. Unlike Winchester Short Magnum cartridges, the Ruger Compact Magnums share the same diameter from case head to body. This allowed Ruger to chamber the cartridge without extensively redesigning their Ruger M77 rifle to adopt them to the new Ruger cartridge.
The .338 Ruger Compact Magnum or .338 RCM is a rimless, short-length rifle cartridge based on the .375 Ruger case. It was designed by Ruger and Hornady and released in 2008 and chambered in various Ruger rifles. The goal was to create a shorter cartridge than the big .338 magnums that would fit in a more compact rifle with nearly the same performance. Similar to the design ideas for the WSM cartridge family, but somewhat narrower which will frequently allow one more cartridge in the rifle magazine than the WSM equivalent. This round is designed for hunting medium to large sized North American game.
The .416 Ruger is a beltless, rimless, bottlenecked cartridge designed as a joint venture by Hornady and Ruger in 2008. The cartridge is based on the .375 Ruger case which was necked up to accept a .416 in (10.6 mm) bullet. It was designed as a dangerous game cartridge particularly for use in Alaska and Africa.