They are based off the same parent cartridge and seems like they are built for similar purposes. Anyone have experience with both? RCM seems like it never caught on. Probably no advantages on any of the big 300s anyway.
Well, actually, the RCM case is the basis for the 6.5 PRC. The 300 PRC is based on the 375 Ruger.
The issue with these is 2 fold. First, the RCM was launched at a similar time as the SAUM and WSM, but with a lower marketing budget. So, it just got chambered and sold less. Remember how exciting the WSM marketing was? I mean people bought them slightly afraid it would hit their elk so fast, it might burn up. Now we know that as a failure in WSM design where they put a big case in a short chamber so they used short bullets, slow twist rates, blah, blah, blah.
In addition, they just designed it wrong…well all the short mags were designed wrong.
Cartridge design is relatively simple. First, you review the market for gaps, issues, new technology to take advantage of. Then you list out your specific targets.
Those will primarily drive bullet design, so pick a bullet or narrow range of bullets. These will set your neck, throat, twist, barrel length, etc.
This bullet needs driven at a certain velocity to perform at both the top and bottom end. Your targets should also tell you your performance bracket hi/lo. This will basical set case volume and shape.
Then test and modify until it meets targets.
At this point, you need to issue a "white paper" to gun makers, action makers, ammo makers to prepare them for launch. Create partnerships to ensure volume and timing.
I'm sure Ruger/Hornady did some of this, but the really missed on bullet, case volume and performance. They chose to back off and not market their way through the failures. Winchester did.
What short mag do we need? One that is WSM diameter, about 0.02" shorter cbtd, runs 175-195gr bullets in a 9 twist….or 8.5 for mono's and has a max oal of 2.95" and hits about 3000fps in those bullet weights.