The .338 RCM (Ruger Compact Magnum)
By Chuck Hawks
For 2008, Hornady/Ruger have introduced the RCM line of short magnum cartridges. RCM stands for "Ruger Compact Magnum," a line of cartridges based on the .375 Ruger Magnum case shortened to allow a cartridge overall length (COL) equal to the .308 Winchester. This allows the .338 RCM to be adapted to existing short action rifles.
The new cartridge has a standard magnum rim diameter of .532". The head diameter is also .532", the case has minimal taper and the shoulder angle is 30 degrees. Case length is 2.015" and maximum COL is 2.840", the same as the .325 WSM. The new cartridge uses standard .338" diameter bullets.
Hornady claims that the .338 RCM offers .338 Winchester Magnum performance in a rifle with a 1/2" shorter action when fired from a standard 24" test barrel. In addition, they also claim that, due to superior powder technology, the .338 RCM offer superior performance to the .338 Win. Mag. from short barreled rifles. (They do not explain why anyone in their right mind would want a short barreled .338 Mag. rifle.)
For their new .338 from a SAAMI standard 24" test barrel, Hornady claims muzzle velocities (MV) of 2950 fps with a 200 grain SST bullet and 2775 fps with a 225 grain SST bullet. These velocities are comparable to those of most .338 Magnum cartridges and, especially with a 225 grain bullet, the .338 RCM should make a fine elk, moose and grizzly bear cartridge.
From a 20" test barrel, Hornady claims MV's of 2850 with a 200 grain SST bullet and 2710 fps with a 225 grain SST bullet. Unfortunately, no mention has been made of a .338 RCM factory load using a 250 grain bullet. It is the heavy 250 grain bullet with its .313 sectional density that made the reputation of the .338 Win. and subsequent .338 Magnum cartridges on heavy and dangerous game, especially in Africa.
Hornady's data shows that these velocities are superior to those obtained with the .338 Win. Mag. in a 20" barrel. This is probably true, but so what? I like to think that I am a reasonably intelligent fellow with a fair amount of experience with .338 Win. Mag. rifles and the thought of shooting a lightweight, short barreled .338 Magnum makes my blood run cold. I have considerable experience with a 7 pound .338 Federal caliber rifle and, although the .338 Federal is less powerful than the .338 RCM, it is too much cartridge for a lightweight rifle! Most shooters find the recoil and muzzle blast of a standard weight .338 Mag. rifle with a 24" barrel unpleasant and intimidating.
Never the less, Hornady and Ruger are betting the future of their new cartridge on the notion that hunters will line up to buy .338 Magnum rifles with 20" barrels. Judging by Hornady's advertising for the new cartridge, it was designed from the outset to offer the best possible performance from a 20" barrel. That is supposed to lure customers away from the plethora of other .338 cartridges.
The .338 RCM does have advantages compared to the .325 WSM. First, it is a true medium bore caliber, not an 8mm. Second, it is not based on a rebated rim case, so its feeding reliability should be better. Third, because the case is smaller in diameter, some rifle magazines will be able to accommodate four, rather than three, cartridges. These considerations make the new .338 RCM superior to the .325 WSM, particularly if applied to rifles with normal length (24") barrels. Whether the .338 RCM is worth the trouble and expense compared to the .338-06 and .338 Win. Mag. will be up to consumers to decide.
Copyright 2007, 2012 by Chuck Hawks. All rights reserved.