I hadn’t ever given much thought to the 300 RCM. Today, I saw a clip of Steve Hornady espousing the virtues of the 300 RCM, and he convinced be it’s a worthwhile cartridge, maybe even a wonderful cartridge. Makes me wonder why it’s not more popular (esp as people become more inclined to desire short barrels to facilitate handiness with a suppressor b/c it’s optimized for a 20" barrel).
Particularly if it’s accurate, seems like it would be very popular…but it’s not. It’s so unpopular that I found only one offering on AmmoSeek - only a single store offering 150 gr (really?) loads from Hornady (which must be old stock b/c not currently catalogued by Hornady) for $115/box
…and no rifle offerings available via Davidson’s.
I think I’m gonna research it a bit more, but sadly not really a viable option unless you really want to handload (you can get brass) AND you have or can get a used or custom built rifle.
Honestly, I think if I’d been in the market for a .300 Win Mag in 2007/2008, I might have bought a 300 RCM instead…and today I’d regret it.
Even if it was available today, probably wouldn’t do well vs all the fast twist, high BC, heavy-for-caliber wonder-cartridges now available.
Submit the question to the vortex Nation Podcast people and see if they respond.
They have a whole series of videos about cartridges that they refer to as lead balloons. Perfectly usable, in some cases Superior to other products out there, but for whatever reason the fickle Market wouldn’t accept them. One that comes to mind immediately to me is the 338 federal. Also whatever the parent case for the 6.5 Creedmoor is.
From what I have gathered, it just didn’t quite live up to the promise of 30 cal magnum performance out of a short action/short barrel. From what I have read, with a 24" barrel you could get magnum performance, but in a 20" barrel it was more like a 30-06 with a 180 grain bullet. The 300 RCM has a smaller case capacity than the 300 WSM, being based on the 375 Ruger versus the .404 Jeffrey for the WSM. In the end, I think the WSM edged it out on performance in the short magnum category.
I’m not trying to advocate for the 300 RCM, but if you match factory loads 300 RCM vs 300 WSM with comparable bullet & same barrel, 300 RCM edges out the WSM (but the differences are nominal).
Also, 300 RCM’s competition is the 300 Win Mag, not the 300 WSM, the latter is effectively a niche market. The 300 Win Mag edged out the 300 RCM by the numbers, but the velocity & energy differences (among all three) are negligible. So selling point of the RCM (and the WSM) over the Win Mag is short action (not velocity & energy), which is good for gun makers as well as gun buyers.
As far as barrel length goes: Had the RCM been successful, then a dozen manufacturers would have produced rifles, and they’d have come in various barrel lengths based on market demand (just ass today you can get .300 Win Mag in multiple barrel lengths).
I think it was mainly an issue of marketing and timing, not performance.
Fair enough about the marketing and timing. My load manual, however, has the WSM about 100 fps faster for the same bullet and powder. I realize the different manuals have slightly different data, but for example with the same 180 grain bullet and RL17 powder the max velocity listed for the RCM (in a 24" barrel) is 2822, but the WSM shows 2934. Now, I could be wrong, but I thought the idea with the WSM was to get (near) 300 Win Mag performance out of a short action. Full disclosure, I am a fan of the 300 WSM. That said, regarding the timing and marketing, perhaps it was a little early for the rise in popularity of suppressors?
==> Thanks for the response / discussion. 
I don’t disagree with anything you’ve said. And just to be clear, I’m no advocate for the 300 RCM. I just think it’s a curious situation (incl & maybe precipitated by the 2005 WSM lawsuit).
I wasn’t looking at multiple entries in load manuals to find the full range of similarities and disparities. I just took a quick look at loads from Hornady’s one 300 RCM load and their two 300 WSM loads. Also compared with their 300 Win Mag 200 gr ELD-X. Seems like not enough practical difference for the vast majority of shots taken, even with handloads.
Arguably, some hunters would have good reason to favor the WSM or the RCM over Win Mag, but 300 Win Mag rifles still outsell the 300 WSM as well as more .300 Win Mag ammo sold.*
After continuing to look at this (I have too much time on my hands), I still think the real issue with the 300 RCM was marketing and probably timing (I also think it would never have been developed had Rick Jamison not sued Winchester and threatened to sue Ruger), but that’s just a barely-educated opinion.
PS - I agree the 300 WSM is a great cartridge. Maybe it would have taken more market share but for the Rick Jamison lawsuit.
==> Thanks again for the response / discussion.
**According to our website host (“Top 15 Most Popular Rifle Cartridges 2023 Edition”), 300 Win Mag outsells 300 WSM in rifle sales and ammo sales.
Yes, thank you for the discussion Similarly, just to be clear, I’m not advocating against the 300 RCM, just personally like the WSM for a compact 30 cal. magnum. On performance you make a good point. At the range I will take shots, there really isn’t a significant practical difference. I think a deer would be equally dead with a good shot from either. As with a lot in our hobby, I think personal preference has much to do with our favorite cartridges and rifles
No doubt 300 Win Mag is still more popular than the WSM by any measure and is a great, dare I say classic, cartridge. From what I’ve looked at, being a fan of the WSM, the lawsuit did hurt the acceptance of the short magnum family. Had it not been for that unpleasantness, perhaps rifle manufacturers would have thrown more support behind the WSM with the factory ammo to follow. I remember for a few years there in the early 2000s short magnums were all the rage in the gun rags. We’ll never know I suppose and the 300 WSM remains a niche cartridge. Anyway, thanks again for the good discussion!