|
Jacketed bullets are groove diameter. That's 451 for the 45ACP. Its standard practice to size cast bullets one thousandth bigger, ie 452 for the 45ACP. That probably dates from earlier times when there was more variance in groove diameter, to give the bullet a beter chance of sealing an oversize bore.
Cast bullets are much softer than jacketed, what's why cast bullets two or three thou oversize can be fired through most guns without excessive pressure.
The nicest 45ACP bullet I've found is the Lee 230 grain truncated cone. I am a commercial caster and have cast lots of them from a six cavity mould. I size them 452 and my customers are very happy with them.
|