Short/compact cartridges, magnum or not, only make sense if the action they're to be used in can also be commensurrately shortened - which the #1 cannot.
Since, with the Ruger #1, cartridge length has little to do with the rifle - and sporting shooters aren't Army grunts that need lighter ammo to carry - why not take advantage of the widely-available .338 Winchester Mag, or .340 Weatherby Mag ?
I like the idea of the 338 RCM and almost ordered a Model 77 in that caliber but there is so little data on that cartridge and from what little found you have to use factory Hornady ammo with the propriatary powder or you are not going to get the velocity you want.
As a handloader and with the available powders you have the same performance as a 338/06. If you want the caliber in a nice RSI then I agree it would be neat but for pure performance it buys you zip....
In the middle of trying to make up my mind a deal fell in my lap on a very nice custom 338 WM for about 40% of what it took to buiild. I still like the concept of the RCM cartridges and I love the 20" M77 with sights but I'm not looking back. I'm going to shoot the hell out of the 338 WM.
What's with the "no need" for a short action caliber thinking?? I guess there is no need for a No.1 in a 223 , 22-250 , 6mm , etc. I only have one and it happens to be in a 25-06 but , I would like one in a 7mm-08 among others just because I have bolt rifles in some short actions that a No.1 in the same caliber would compliment quite nicely.
As far as cartridge length having little to do with a No.1...who cares?? There are a lot of shooters out there that either don't want or don't need a mag/long action caliber for their intended purpose. To someone that doesn't have many rifles but wants a No.1 in a caliber they already shoot or reload for it makes perfect sense. While others just don't care for the added recoil when a lesser caliber can get the same job done. There are plenty of other reasons but you get where I'm going here?
Granted you don't gain with a shorter action, but if you put a 338WM or a 340WBY in a compact 20 inch barrel, use lose lots of velocity, and gain muzzle blast. These cartridges shine with a 26" barrel. Again, the 338RCM was invented around a 20" barrel. OK, how about they they chamber it in the MKII 77 RSI. Then you are getting a shorter action with a short barrel. I would like to see either, although I would prefer the single shot.
make mine a 358 win blued though as i think stainless #1s look cheesy. A classic looking gun should be made out of space age stainless or laminated or synthetic materials. Blueing and walnut thank you.