My bet is, Turnbull's will give you a quality barrel with a .458 diameter bore.

While not intimately familiar with Turnbulls, I would guess that a mold that throws a .460" diameter bullet will do you just fine. Being .001" - .002" oversize from bore diameter is good, .004 over is getting into risky territory as you will be sizing them down a lot.

I have three rifles with .458 bores, one Marlin 1895, one custom Mauser in .458WM, and a Shiloh 1874 in .45-70. All three prefer nothing larger than .460. The Shiloh, since I'm shooting Holy Black in it, even shoots .456"-.457" plain base bullets well.

I have a Lyman 405gr mold that throws .460" bullets if you would like to try it before you make any final decisions.

Ed

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