The 300 Ruger Compact Magnum, often known as the 300 RCM, is a rimless, short-length rifle cartridge designed to closely resemble the performance of the classic 300 Winchester Magnum cartridge, but chambered in a short-action rifle. Hornady and Sturm Ruger collaborated to produce the rifle cartridge for hunting medium-to-large North American game, which was introduced commercially in 2008 and chambered in a variety of Ruger rifles.
It employs a rimless design case based on the powerful 375 Ruger cartridge, which has the same base and rim diameter of 532 in (13.5 mm) as belted magnum cases based on the 300 H&H Magnum and.375 H&H Magnum. Given cases of identical length, this design allows the 300 Ruger Compact Magnum cartridge to have a larger case capacity than a belted magnum case. The case length was lowered to 2.10 in (53 mm), which is close to the 308 Winchester case since Ruger wanted the cartridge to be chambered in short length bolt-action rifles.
Hornady produces high-performance ammunition for the 300 Ruger Compact Magnum cartridge. The Hornady Superformance Ammunition travels at 3,040 ft/s (930 m/s) with a Hornady 180 gr (12 g) Interbond or SST bullet and 3,310 ft/s (1,010 m/s) with the 150 gr (9.7 g) SST bullet. The higher case capacity and "short fat" cartridge efficiency of the 300 Ruger Compact Magnum result in gains in the neighborhood of 150 fps above the H&H cartridge, and it performs similarly to the 300 Winchester Magnum or 300 WSM.
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 Sturm 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 .338 Ruger Compact Magnum uses a unique case designed by Hornady and Ruger based on the powerful .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 as 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 M77 rifle to adopt them to the new Ruger cartridge.
