Hi Marlinlover...I used a 4 jaw chick and a dial indicator setup...It's really not bad IF you have good equipment...I don't.

The other ideas posted here are worth thinking about too.
Dale

Hi Marlinlover....Here's your chance! Use your lathe! I chucked a 200 grain 30 Lee up in the lathe ( took about 3 hours to get it 'right' (without handles) and cut the nose to .301 from .295. It was only off a little... ( off on one side at the nose a little and off the other side next to the body a little!)It still shot wonderful. You would be cutting next to the base....It would be good practice....& you could maybe do it with a formed wooden dowel and some sandpaper if you were careful... I can think of a number of things I would try before I threw it away..... Oh course, after I work on it...then I would have to throw it away Danger!...working on molds is expensive and frustrating.... Dale

If it was me, I'd just lap/hone the gas check shank with a boolit from the mold and some lapping compound trying to keep it mostly on the check shank. Regards, Woody

I'd still call Lee and tell them your dimensions, and when you bought the mold (don't think it will matter) and see what they say.... my bet is that they will say "send it back" and they will send you a mold that is correct.... Lee has a good reputation for working with casters....

marlinlover,
30 cal straight shank should be 0.284 - 0.285", for Hornady checks.

45 cal straight shank should be 0.424 - 0.425".

If the shank is tapered then it will likely need to be a little bigger. And then, different people have different ideas about how tightly a check should fit, but your numbers sound very small.

Thanks mountaingun...

That's what I thought. The Lee molds are under cut and that sucks.

I like Lee alot and use lots of their products as well as many other manufacturers. But Lee is supposed to be quality, and work for the new guy, but an undercut mold certainly is not user friendly.