Home Forums Reloading Big Game Rifles 338-06 to 338 RPM? Same barrel?

Like the title says, can a barrel already chambered for 338-06 be rechambered for 338 RPM? Could be a fun project. Brass is expensive, but available.

Barrel in theory should be able to be rechambered but you'll need a different bolt as the RCM will require a different larger bolt face.

I believe the RPM has the .473 bolt face like the 338-06. It's rebated. .473.

Looks like a .473 case head to me. Might you be thinking of the Ruger Compact Magnum instead of the Weatherby Rebated Magnum?

I'm not seeing anything at first glance that says the barrel couldn't be rechambered and work. Feeding might be (or not) an issue.

Cheers,
Rex

It may not work unless the barrel is set back about .300. I think the chamber neck diameter on the .338-06 is both wider and the chamber is shorter than that of the SAAMI .338 RPM. Therefore, the RPM reamer might be too narrow at the neck and the case longer, so you may get a step near the end of the neck, unless the barrel can be set back. Check carefully the chamber neck diameter on both for differences. I think the RPM is .366 to .365 and the .338-06 about .369 or .370. Also check how much meat is in the barrel and if it can be set back .

Yep, an oversight on my part. I read the OP too quickly and assumed he was questioning the 338 RCM. I apologize.

I think the RPM would be an awesome cartridge

Good info. Might just rebarrel to 338 RPM if rechambering doesn't pan out.

338-06 brass is cheap thanks to 30-06. Why would you even want to go to more difficult to find brass thats exotic and spendy? Is there any real case capacity difference between 338RPM and 338-06?

I've got 338win and 338RCM and really like both but currently there's no supply of brass other that I've stocked up on. Seems 338-06 would be the choice for economy and logistics to keep it running.

338 RPM head stamped brass is easier to find than 338-06 head stamped brass, (although I have some). I also have 30-06 necked up and 35 Whelan necked down brass. Why? just more speed and power, plus something new and fun. Yes, there is a case capacity difference with the RPM on par with the 338 Win.

I found Peterson brass in 338 rpm for about 2 bucks each. This brass is unbelievably consistent in weight as well. It feeds fine from a Kimber 25-06 84L magazine as well.

My proposed project is a Rem 700. Nice to know it feeds well in your Kimber. I was thinking a 210 TTSX would be ideal, what bullet are you loading that feeds well?

I'm just beginning load development. I want to develop a long range load for Nosler Accubonds in 200 grain first, but I'm waiting for bullets to arrive. In the meantime I've got some "medium" loads waiting that use a 160 Barnes ttsx.

I would be interested to know if the 338/06 chamber/neck area could be cleaned up by turning the barrel back some? I'm having my 338/06 reamed out to the Ackley Improved, but I considered the RPM. Just because it IS that close to the Win Mag is why I didn't. I grew tired of the heavier rifle/harder kick in the 338 Win Mag. At the ranges I shoot, I don't need/want the magnum.

Did some shooting of the 338 RPM today. This is the 18" barrel with the brake installed. Scoped with a Primary Arms GLx 2.5-10. Trigger is light, no creep, breaks clean. Chevron center aiming point in scope is very good for fine work on 10x. Does not obscure the bullseye, it's below it. Brake does an excellent job managing recoil. None of the loads I tried are what I would consider harsh with the brake installed. Very nice to shoot with hearing protection, Walkers. Had a few positives for load development and quite a few not good groups. Did not set up the chronograph. Some of the light loads shooting 160 Barnes ttsx shot well enough and are either overlapping the 200 Accubond loads or close to it. I did not hit nervana but it's what I would consider reasonable progress. Here's a few targets.

Keep us up to date on your progress, please Fireball.

I want to add that I had a Remington short action rebarreled with a Midway supplied "Adams & Bennett" #3 in a short chambered .260 Remington. I had it reamed out to the 6.5/284 Winchester. That particular rifle had feeding issues, but my point being is the RPM is just a "lengthened" .284, and should be as easy to chamber for.

did that, works great. had to alter rails. just under 338 mag vol.