Why? Are the bores that bad?

To do a re-bore, you have to go up X amount. Cliff LaBounty has re-bored quite a few .350 doubles to 9.3 for Paul Roberts, so I would imagine .450 to .465 would work. The other issue is, of course, wall thickness. It would be insane to do one of these without reproof.

Also, check case dimensions. Although they use the same basic case, in comparing rounds of original Kynoch, the .450 shoulder appears to be quite a bit farther forward than that of the .465.
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