ORIGINAL: Pavomesa
The danger of new things like this is if you get to Africa and somehow your ammunition doesn't make it with you, you'll end up throwing rocks. Whereas if you had say the traditional 375HH, you can always buy ammo as needed and be assured from past experiences that it will work wonderfully well. I think ultimately this new cartridge will be received with a big yawn by the shooting world just as many similar cartridges before it.
I agree with pavo on the ammunition side, but as far as how it will be received its acctually been received rather well. Initially, all the gun writers and big wigs scoffed at something listed as an "improvement" to the 375 H&H. Why mess with 100 years worth of damn near perfection? Craig Boddington said the same thing... he acctually wanted to see the 375 Ruger fall behind in testing and shoot poorly, just because he is such a fan of the H&H. But when he shot it, he changed his mind. And openly admitted his initial bias to boot.
Not that I think anyone should sell their collections to buy something Craig Boddington endorses... but the man has seen just about everything with rifles, and if I get to go to Africa hunt just 3% of the amount he gets to, I'll die a very happy man.
I've never been a big fan of Ruger rifles. I do like the No. 1s... but the Hawkeyes have started to change my opinion... controlled round feed, solid actions... standard length and equal or just a smidge over the power of a 375 H&H.... I gotta be honest I kinda like it.
There isn't a huge market for .375s in the US. Or anywhere for that matter. Huge is a relative term. There is certainly a market for it... but you won't see the .375 Ruger taking over the 30/06 as king of sporting rifles.... not by a long stretch. Market is definately there though. I think you'll end up seeing this one stick around, especially since it will be so easy to chamber a standard action receiver in the cartridge. If all a rifle maker has to do is ream out a barrel to offer another cartridge... its a lot more simple that retooling.
I'm not quite as sure about the 300 and 338 RCMs though.... I think those may have been better left to the wildcat crowd to play with.