The .300 Ruger Compact Magnum is a rimless, short-length rifle cartridge

Cartridge (firearms)

A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...

 designed for the hunting of Medium-sized North American game. It is designed to closely duplicate the performance of the historic .300 H&H cartridge, yet to be chambered in a short length action rifle. The cartridge was designed by Hornady and Ruger in partnership and released commercially in 2007 and chambered in the various Ruger rifles.

Design & Specifications

The .300 Ruger Compact Magnum uses a unique case designed by Hornady and Ruger. The case is of a rimless design having the base and rim diameter of 0.532 in (13.5 mm) which is the same diameter of the belt on belted magnum cases based on the .300 H&H Magnum

.300 H&H Magnum

The .300 H&H Magnum Cartridge was introduced by the British company Holland & Holland as the Super-Thirty in June, 1925. The case was belted like the .375 H&H Magnum, and is based on the same case, as also is the .244 H&H Magnum. The belt is for headspace as the cases' shoulders have a narrow...

 and .375 H&H Magnum

.375 H&H Magnum

The .375 Holland & Holland Magnum is a powerful rifle round and one of the best-known and most popular medium-bore cartridges in the world. The .375 H&H was only the second cartridge ever to feature a belt, now common among magnum rounds. A popular misconception is that the belt is for headspace,...

. 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 shortened to 2.1 in (53.3 mm) which is similar to the .308 Winchester

.308 Winchester

The .308 Winchester is a rifle cartridge and is the commercial cartridge upon which the military 7.62x51mm NATO centerfire cartridge is based. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62x51mm NATO T65...

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 M77 rifle platform to adopt them to the new Ruger cartridge.

While the .300 H&H Magnum is longer than the .300 Ruger Compact Magnum, the latter cartridge has a greater case capacity than the former. This is due to the .300 H&H Magnum having a long tapered body while the .300 Ruger Compact Magnum follows modern cartridge designs in that it has very little taper and a sharper shoulder. The dimensioned drawing is of the parent case .375 Ruger.

Performance

Currently Hornady and Double Tap manufacture ammunition for the .300 Ruger Compact Magnum cartridge. The Hornady superformace ammunition drives a Hornady 180 gr SP-RP bullet at 2840 ft/s (865.6 m/s) and the 200 gr DGS and DGX bullets at 2660 ft/s (810.8 m/s). The.375 Rugers slightly greater case capacity, and the "short fat" cartridge efficiency lead to increases in the neighbourhood of 150 fps over the H&H cartridge. Their capabilities remain essentially comparable.