Re: Vanguard S2 in 257 Weatherby?
The Weatherby cartridges do have freebore but the 257 case is only 2.549" long. The mag box of a Vanguard is 3.565 on the insde. That leaves 1.016" for bullet projection. If the freebore is less than .300, that should allow available bullets to be seated to the lands and still fit the mag. That said, the Weatherbys seem to shoot well with freebore and a good jump.
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