Only way to find out is to cast some, Rob. Even moulds from the same maker can differ as tools wear, etc. Even though pure lead is the recommended metal, you could add a small (1%) amount of nobler metal such as tin to cause the bullets to come out of the mould slightly larger.
I prefer to open them up as needed and size down.
BTW - Don't bother asking the RCBS engineers about it. I had a .578 Hodgdon mould that threw them out at .576 and called to see if they would replace it. I got into a heated discussion with a guy who insisted that N-SSA shooters never size their minies. The customer service rep ended up gifting me a different mould.
Bob Anderson
Company C, 1st Michigan Volunteer Infantry
Small Arms Committee
"I won't be wronged. I won't be insulted. I won't be laid a hand on.
I don't do these things to other people, and I require the same from them."
- John Wayne in "The Shootist", 1976
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