Pre 64 model 70 .300 WBY MAG

International Harvester

International Harvester

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I recently purchased a well used pre 64 M70 in .30-06. It's by no means collector grade so my question is if I had it re-chambered to .300 WBY MAG could the old action safely shoot Weatherby brand ammo? I always figured you needed a 9 lug Weatherby M5 action to handle that stuff.

Regards IH
 
It gets shot pretty regularly in weatherby vanguards and remington 700's, which both share a pretty similar design as the Win mod 70. I don't think it would be an issue but I'm no expert. Probably best to ask a knowledgable smith.
 
Safe? Sure.

Your magazine box and receiver opening are a quarter inch too short though.

300 win mag is an easier conversion
 
rgv said:
Safe? Sure.

Your magazine box and receiver opening are a quarter inch too short though.

300 win mag is an easier conversion
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That's why the 300 Win was developed... same performance, slightly shorter oal.

But you would also need to alter the bolt face and extractor... getting to be an expensive alteration... re barrel it to a standard caliber and use it or sell it to someone who will is your best bet.
 
International Harvester said:
I recently purchased a well used pre 64 M70 in .30-06. It's by no means collector grade so my question is if I had it re-chambered to .300 WBY MAG could the old action safely shoot Weatherby brand ammo? I always figured you needed a 9 lug Weatherby M5 action to handle that stuff.

Regards IH
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Dummies have been rechambering Pre64 M70s to 300Wby for years. Usually they were 300 H&H to Wby as it is an easy rechamber job. There's more fooling around to using a standard length case with a standard bolt face but it's not overly difficult.

There's nothing special about the Mark 5 action...don't be fooled.
 
Kevan said:
I know this is off-topic but I have seen and handled several Mod. 70s that were originally made in 300 H&H and their respective owners had them rechambered to 300 Weatherby.
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But they didn't start out as 30-06's with shorter magazine boxes, springs and followers and standard bolt faces and extractors (which is what the original poster has and inquired about)... the 300 Weatherby is based on a 300 H & H blown out.
 
guntech said:
But they didn't start out as 30-06's with shorter magazine boxes, springs and followers and standard bolt faces and extractors (which is what the original poster has and inquired about)... the 300 Weatherby is based on a 300 H & H blown out.
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But aside from swapping parts and opening the bolt face it's relatively simple. The action is already long enough. A reasonably competent lay person can do all the mods in their own shop, except the rechambering and opening the bolt face.
 
Thanks for the info folks! I was aware of the length issues but just wanted to get opinions on strength. I always figured weatherby brand ammo belonged in weatherby guns. I know, I know.

After coming to my senses I think I'm gonna leave it as is and just use it like a rented mule. I can't bring myself to mangle these old horses!
 
The folks that re chambered the pre 64 300H&H to the weatherby are heretics that obviously need to be spoon fed green jello.
IH, it's an expensive ordeal to accomplish what you are looking to do. Your be better off to use another donor more suitable like a New Haven originally so chambered.
 
rem338win said:
The folks that re chambered the pre 64 300H&H to the weatherby are heretics that obviously need to be spoon fed green jello.
IH, it's an expensive ordeal to accomplish what you are looking to do. Your be better off to use another donor more suitable like a New Haven originally so chambered.
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That's the word I was looking for...Heretics.
 
Just as an aside, if you were to do this, which I personally think is a great idea, one must throat it as a factory 300 Wby , in order to use factory Wby ammo..........ie about 1/2" freebore, or you can run into serious pressure problems and possibly even crack that old POS action.

The new CRF Win/FN actions are 10 times the action the old pre 64s are, by the way..........
 
c-fbmi said:
Just as an aside, if you were to do this, which I personally think is a great idea, one must throat it as a factory 300 Wby , in order to use factory Wby ammo..........ie about 1/2" freebore, or you can run into serious pressure problems and possibly even crack that old POS action.

The new CRF Win/FN actions are 10 times the action the old pre 64s are, by the way..........
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Holy Smoke !! I wonder how many old Fudds ( pre-64 lovers ) are now on the way to a Cardiac Care Unit after that comment ??
No worries, I'm not one of them.... why ?.... because my 300 H&H is a 721.....
 
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