Is this a parts gun???
Barrel is stamped 264 WM but under the recoil lug it is stamped 458.

Bolt does match serial number

Perry

No; it just means it was a 458 Mag length action, meaning it is a standard mag length; not a 375 length. Remember, the 458 was the first of the, what we now call, the standard length magnum cartridges; its offspring like the 7mm, 264, 338, all came later than the 1956 458 date.
Ok, not including Weatherby.
Not to worry.

Thank you!
Love learning new stuff.

Perry

Yep that is how you know you have the real McCoy. Lack of 458 would be a parts gun made from a non Magnum action.