Ran across one last night in .30/338. I know that cartridge is similar to the .308 Norma and heard the Norma data can be used to load it (I know, start at the bottom & work up carefully). My questions are: Will a .300 Win Mag reamer clean up this chamber to something more readily available? If not are these actions typicly strong enough for something like the .458 Win Mag?

Didn't take a real good look @ the bottom metal so I don't know if it is an '03 or '03A3.

Dear Joe,
The dia. at the shoulder of the 308 Norma "should" be .489 and the Win mag .491 thus the Win Mag reamer should clean up the chamber. The real beauty of the Norma is that you can EASILY make cases for it from 338 Win Mag brass--easy to get and reasonably cheap. Just run the 338 cases into the 308 Norma dies and load and shoot. The cases will be a few .000s short but it will not matter. Also the OAL of the Norma is better suited to the Springfield magazine than the 300 Winny. Velocities are almost identical and I shot a 30/338 for many years in 1000 yd competition and it was right there with the Win Mag. If you do NOT want to reload then rechamber to get the easy to find 300 Win.
Aloha, Mark

You asked if a Springfield action is typically strong enough for the .458 Winchester cartridge.

I have a .458 Winchester built on a Rock Island high number '03 action which has never been a problem.

It was barreled by the late Paul Marquart with a Bill Atkinson barrel , (the "A" and the "M" in the "A&M Barrel Company") an outfit of some fame among shooters from the 60's through the late 70's. I know Paul didn't have any concerns over it. But, he might have had if it was a low number action. As I don't know which your current question is referring to, I have nothing to add to that.

I also have a .30/.338 AND a couple of .300
Win Mags. Personally, I prefer the .30/.338, but there is nothing fundamentally wrong with the .300 Winnie either.

As the '03 actions were not originally built specifically for feeding belted magnums, whichever chambering you choose for either an '03 or an '03-A3 MAY require anywhere from "0" to "oodles" of 'smith work on the rails, ramp, & bolt face to feed perfectly...particularly with the larger diameter blunt slugs of the .458 Win.

It's luck of the draw as to where your beginning point is. A good 'smith experienced in the work can make any of them work pretty darned good...

Would add that IMO a high no. 03 action, double heat treat, is far preferable to an 03A3. Much smoother and better finished throughout, and plenty strong enough.

I was thinking of this as a possible rifle for my future son-in-law. He is going to be joining the military after he graduates law school and that is the prime reason I was thinking of this rechambered to .300 Win (he has some military experience so he is not a beginning shooter). He could find ammunition for it anywhere he would be stationed. I thought on the chance I would get it & keep it I would like to have it rebarrelled to .458 Win Mag. It is already set up for the .30/338 so it should be a simple rebarrel job.

WyoJoe- With that additional bit of info from you about who the rifle is to be used by, I think the .300 Winnie is a really excellent choice.

It very likely will feed well enough for general use without any additional tweaking.

BUT, it may still take some little bit of aid. The location of the start of the shoulder is different on the Winnie than on the .30/.338, and it is surprising how little difference it sometimes takes to screw up smooth, perfect, feeding without the attention of an experienced gun guru.

But, I'd go right ahead if I was in your shoes. As long as the work isn't over done by an amateur, I doubt you'll have much, if any, trouble.

(Of course, all this assumes that it feeds well NOW, as a .30/.338. If you are allowed to, I think you'd best check that out before laying your money down for the rifle to start with.)

Don't do it! The 308 Norma is and excellent cartrdge.

keep it 30/338 and get a set of dies .. if it don't shoot, then mess with it.