mould lapping

[Frank46]

I have lyman's only gas checked 45 cal rifle mold (don't remember the mold number) and wish to open it uo to get ..460 dia boolits. This is for my ruger #1 in 45/70. As cast dia. is barely .459 if your lucky. What grade lapping compound should I use to do the lapping. I have grades from 220 to 1000 grit.
Thanks Frank

[shooter575]

600 is my finest.That is smooth enough I think? With only .001 to remove I would start with 3-400.do a final in 5-600. Iron cut a LOT slower than Al.

[Frank46]

Shooter575, thanks for the info. Garage is a mess right because of the hurricane stuff I dragged out. supposed to get cooler here in La but don't believe it. Still have all windows covered right now as there is another storm in the atlantic and its destination right now is uncertain. Been having breathing problems lately. So have pretty much kept inside except to take the wife shopping. Frank

[Buckshot]

...........Frank46, remember too that lapping the cavity will have a tendancy to blur the sharp corners a bit. Depends on how much you lap.

..............Buckshot