new mold and dies???

[mikeym1a]

G'morning, all. I recently got a couple of new molds and sizing dies, and have a question, or two or three. I got a new lee mold in 8mm, and a .323 sizing die, and others. The new mold throws a boolit of .323. When I used the sizing die, the boolit came out precisely .323, and that started me wondering. I'm new to casting rifle boolits, and from what I've read, the finished product should be .324, for proper fit and seal. Is this correct? Also, I got one of the new generation molds from lee, .312-155-2r. Really nice mold. I cast a few in pure lead from it for bore slugs, and what came out ranges from .305-.309. Paul Matthews, in his book 'The Paper Jacket', says that pure lead alloy comes out smaller in the same mold than alloy. Is this why the .312 is coming out small?:veryconfu

[Echo]

I assume that you are casting for an 8mm Mauser, and those bbls can vary some- therefore, sizing to 1-2 thousandths over groove diameter will require slugging the bore. And if the bbl is old, a chamber cast, or slugging the leade, might find an oversized leade that will require an oversized boolit. The boolit must seal the bore.
And pure will cast smaller than alloy, but minimally - pure Pb vs WW+2$Sn might have a difference of 1 thousandths (+/-) with normal sized boolits, depending on the alloy.

[mikeym1a]

This is one of the La Corona Mausers, spanish made. The bore looks really nice. Haven't done a bore slug yet, nor a chamber cast. But, plan to. Re-arraigned my room recently, and haven't been able to find by heavy aluminum ramrod. Don't want to put a steel one down the barrel of any of my guns. I guess what was asking was, shouldn't these boolit molds put out a slug at least 1thou over the stock size? And the sizing dies, the same? I've read that that is what is necessary to seal the bore, and I want to do this right. Thanks.