On another forum a gent has posted pictures of a reamer and head space guages marked 458 Express #2. No manufacturers name on the tools.
Appears to be for a rimless, unbelted case. Can any one help us with the correct brass to be used for this cartridge? Further dimensional details on the Gunsmithing forum in castboolits.

jeffe: thanks for the link . Don't think that is the one though. His reamer indicates about a 3" case length but fatter than the standard mag cases, no belt, not as fat as the big Weatherbys, has a shoulder. What does a 416 Rigby measure at the base?

remember, a reamer is larger than the case... a rum based round would have about a .553 base, a 404 would be about .547, a rigby about .593, and a turned down, following to the case, might be about .585 ..

if not as big as a webby, it is prob either a rum or 404 based

Thanks Jeffe_ I'll pass it on to him. Sounds like 404 is closest but that may be just a few thou big too.