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your winchester model 70 was made by winchester in 1972.
Winchester makes the Model 70
Winchester
1965
There was no 300 Winchester Magnum cartridge in 1939. A 1939 Model 70 would be marked "300 Mag"...and it will be chambered for the 300 H&H Magnum cartridge. There was no other 30 Magnum cartridge in 1939 in the Model 70. The 300 Winchester magnum cartridge was introduced in 1963,...the last year the Pre'64 Model 70 was made. Your 1939 Model 70 may have had a later barrel swapped in to it. 300 Winchester and 300 Win Mag are the same cartridge.
Go to Proofhouse.com and look at the Winchester sn data.
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The 7mm Ultra Mag is a Remington cartridge. THE model 70 is a Winchester rifle. Winchester does not chamber the Model 70 For the 7mm Rem. Ultra Mag cartridge.
$1500
100-1000 usd
Would greatly depend on condition.