Depends what you want to use it for as the 350 RemMag is best with bullets no heavier than 225gr (the Nosler excels) and you should be able to get 2650-2700fps out of that bullet depending on barrel length and maybe 150fps more using the 200-210gr bullets. Remember the 350 RemMag has basically the same case capacity as the 30/06.

The 338WSM "should" give you pretty close to 2950fps with the 200-210gr bullets....bigger I don't know....but you must form the brass and handload every round whereas you "can" buy ammo for the 350 RemMag.

If you like the 35-caliber why build a 350 WSM which should give you at least 100-150fps more than the RemMag?

I'm presently working on an MRC for another 338WSM, with a 22" Pac-Nor tube. On the WSM you'll have 83g water capacity with WW brass and 81.8g with Norma. It's no problem to expand the necks on 300WSM brass out to 338. They thin out about .0004". Incidentally, I also checked water capacity on expanding a 7mmWSM. They turned out identically to the 300 brass @ 83g water. That brass was a bit heavier so I'm guessing the web is thicker but I didn't split the case I had, to tell for certain. They were about 9g heavier than the 300WSM.

You'll have a good bit more powder capacity than the 350Rem Mag so you will get higher velocity. I safely get about 2830fps with 225g bullets, 2900fps with 200's and just under 3000fps with 185's, all in a 21" tube. Because you need to seat 250's pretty far into the powder chamber in a short action, those bullets aren't practical except for short range hunting. You can't get enough of the slower powders to push them much over 2600fps and you start getting pressure signs near the same velocity with faster powders.

To me the choice is a no-brainer. Dies are available from Forster and Redding. I had mine made up way back when, by Hornady mainly for their tapered expander but I also have a Forster sizer that works quite well for making the cases. The operation is no more complicated than when you run your expander through any new brass before loading. Reamers are available off the shelf from Pacific Tool and probably others. Their designation is 338/300WSM.

The one I do have on a M70 action has taken two elk at 300 yards using Hornady 225's on one and Nosler Partition 225's on the other. Worked quite well. Bear in mind those velocities mentioned are with a 21" barrel. My new one should give a few more fps with the 22" tube.

Thanks to both of you!

Bob
I've found RCBS 338 WSM dies for around $25 and 300 WSM brass is about the same price as 350 mag.....what I really needed to know was how the 338 WSM performed out of a short barrel. What is your experience with the WSM feeding from the MRC magazine? What powders are you using in yours? Would you mind sharing your pet loads (PM if you don't want to post)? What stock do you intend to use with the MRC action? I checked both PacNor and MRC websites and both will chamber for the 338 WSM, so that isn't a problem.....I'm thinking about building this rifle to hunt Alaska for black bear and maybe moose....sounds like the 338 would do exactly what I want!

Careful with those RCBS dies. Long story, but they may NOT be the 338WSM. The body will be far shorter and won't match the 338/300WSM reamer. Be sure when you buy them that they match your reamer. Remember, this is still a wildcat. Things don't have to be uniform and the same.

The performance I gave you WAS out of a short barrel. What more could I say? It's good.

I've not had feeding problems with any of my short fats out of M70 short actions. Haven't seen any problems with the MRC action but I do have to polish both the feed ramp and the rails. I don't have it set up yet so I'm not competent to comment, but I don't expect a problem and it's certainly solvable if there is one. It feeds fine now without barrel and stock.

As I told you earlier, the powders I've used are in the range of H4350 �. I have data from H380 up to and including AA3100. The latter was way to slow, too compressed and too slow, the former was a bit fast, but accurate. I also know someone using even RL15 with some success but the velocity isn't optimal.

N560, H4350 and IMR4831 worked well with 210 to 225's. H414 and 760 worked well with 200's. You'll just have to see what your barrel might like. H4350 seemed the best for everything but not the premier powder for various bullet weights, yet it worked with all. I can give you specifics if you like but that's kinda stupid as your mileage may vary. All these powders mentioned worked at between 68g and 73g. I'll share anything I have it it will help you.

Just be certain of a match between your reamer and your dies. RCBS produced a bunch or dies (168 I believe,) based on an order from Olin while they were trying to develop the cartridge. Their order was for a longer neck and shortened body. RCBS had to recall them when the case capacity didn't even equal an '06 in velocity and Olin shelved the project. Incidentally, there is a possibility the cartridge will be introduced as factory around the time of the SHOT Show. Make sure the dies you buy are a 338/300WSM.

I know Pac-Nor uses Pacific Tool reamers. Verify that and go for it! You'll have a cartridge and rifle which will shoot just below velocity of a 338 Win Mag and be a lot lighter to tote.

I've got an MPI stock that is virtually identical to the M70 Featherweight tupperware stock. Those stocks fit me well. I'm going to knock the schnabel forend off of it and shape it like most other stocks.

Except for the fact it's still a wildcat, I think the cartridge is perfect for what you seek. Holler if you hurt!

GonHuntin,
Send me a PM if you decide to part with the 350RM brass.

MtnHtr