Re-Chamber .300 Win Mag to .300 Weatherby Mag?

[pertnear]

I'm asking for a friend...really!

There is a really nice, sort of rare, low-mileage .300 WM for sale that he is interested in. But he is only interested in a .300 Wby Mag. For me, the Win cartridge would be a much better choice with many advantages over the Wby with both being ballistically identical. But we each want what we want...

Could a "skilled" gunsmith rechamber the .300 WM without set-back to .300 Wby? I've been looking at chamber drawings. I may be a mistaken, but the Wby cartridge is a tad bigger in all places(?)

 

[jackieschmidt]

Years ago shooters could buy a kit that allowed one to convert 8mm Mausers to 8mm/06. It came with a reamer, a headspace gage, and a T handle extension.
It was labor intensive, but the results were satisfactory.

So yes.

Finding someone to do it might be the trick.

 

[Kurz]

There is a really nice, sort of rare, low-mileage .300 WM for sale that he is interested in. But he is only interested in a .300 Wby Mag.

It seems to me that his fascination with the .300 Weatherby cartridge will negate the 'sort of rare' status of the purchase since the rechambering changes that rarity permanently.

 

[V35]

It can and has been done. A good friend of mine bought a used rifle clearly marked 300 WM at a gun store in Decatur Tx. He shot it, said it didn’t seem right, and when he ejected the casing it had a round radius shoulder! It shot 300 WBY ammo real well.

 

[jackieschmidt]

It can and has been done. A good friend of mine bought a used rifle clearly marked 300 WM at a gun store in Decatur Tx. He shot it, said it didn’t seem right, and when he ejected the casing it had a round radius shoulder! It shot 300 WBY ammo real well.

When I used to shoot at the old Lake Houston Gun Club years ago, we would find 300 Winchester cases on the ground with hardly any neck.
It was shooters shooting 300 Win Mag ammo in a 300 Weatherby.

 

[ISS]

Tell him there is a MKIV 300 Wby Mag for sale here (not mine) for sale for $750.

 

[Sniperhandle]

Tell him there is a MKIV 300 Wby Mag for sale here (not mine) for sale for $750.

I believe that is a vanguard for sale.

 

[ISS]

You are probably right. Either way, it will be less hassle than redoing a 300 WM.

 

[pertnear]

The rifle he is interested in, that I stated as "sort of rare", is a Ruger #1. It is only rare because the round count is so low & the price with scope is so low. If I didn't already have too many rifles I would buy it as a build donner.

 

[Ledd Slinger]

Nothing much to be gained there. The 300 Win Mag is actually capable of some really fast speeds when pushed with the right powers. Ive had 180gr bullets leaving the muzzle at 3260 fps and the primer pockets on the cheap Winchester brass i used back in the day still held up!!! So I see no sense in re-chambering from one “belted magnum” case to another when the 300 Win Mag can do just about anything the 300 WBY can for speed.

If anything, I would recommend re-chambering to the 300 PRC, but that wont be much gain on speed over the 300 WM either. The 300 WM is actually a great round for speed and accuracy if a person knows how to load for it

 

[Walt Krafft]

When the 300 Weatherby first came out, there were a lot of M70 Winchesters in 300 H&H rechambered. That was a significant improvement. From 300WM not worth the effort imo.

 

[ISS]

Heck, just go whole hog and rechamber to the 300NMI. No belt to mess with that way.

 

[pertnear]

My thread kind of got lost in the weeds. There is no debate that if someone wanted a BIG .30 cal the WM or Wby are equal performers. My thinking (question) is could a gunsmith unscrew the barrel & without shortening or re-treading the shank, run a .300 Wby reamer in & create a clean chamber. Then re-install the barrel to its original alignment. I'm thinking the answer to my question is "Yes" it could be done.

Thanks everyone for your responses. (BTW: what is a 300NMI?)

 

[Walt Krafft]

I think the answer is maybe. The body diameters are close.
300 Norma Mag Improved.

 

[WesG260]

Pull out a reloading manual and figure out if the WBY will clean up a WM. As already noted, the 300 and 375 WBM were designed to 'improve' the H&H cartridges.

I think I may have an original box of 375 buried somewhere. Was gonna go that way ... until my right hand started shaking ...

Nerve damage?

 

[AckleymanII]

300 WM, 180g=3100 fps
300 Weatherby 180g=3300

I have never had to mess with a belt.