Mold diameter ordering question

[Drew P]

So, a gun needs a certain diameter boolit to be happy. So we can order molds to suit that. BUT, if we are going to push every boolit though a sizing die anyway, then why wouldn't we want our molds to cast the boolits grossly oversized, and then we size them down as needed?

Example: I have a few 45acp, and a 45colt that could all take the same boolit in different diameters. So, I could order the mold in like .455" and then size down to any dia I want.

[s mac]

I feel that the least sizing required the better off you are sometimes trying to size a bunch you can take more off one side than the other. Besides, it's hard to have too many moulds.

[reddog81]

Sizing down too much causes problems. The lead you size has to go somewhere and once you size more than .003 or more the bullets start have flashing hanging of the base of the bullet and such.
.455 might be close enough to work for ACP and Colt rounds but I have no experience with 45 Colt.

[country gent]

Over sizing a bullet can cause distortion and an off center condition due to nose and grease grooves not being sized with the driving bands. Also Semi autos are sized to groove dia of barrel whle revolvers are sometines sized to cylinder throats dia. SOme feel any sizing destroys a bullet. sizing down from .455 to ,452 is .003 in dia and may be doable. ( a custom sizer with a little more lead angle might help here) and .455 to .454 is .001 right where you normally want it. Hard bullets sized .003 may require 2 passes or require some force to size down in one pass.

[osteodoc08]

Also, dont forget that the SAAMI spec for 45 Colt is .452 and has been for decades. Unless you are shooting a revolver with a known large groove diameter (older colt); I prefer to size down .001" to even it up and avoid problems