Welcome

Thanks.

Thanks for the comment and watching. I am aware of shrinkage. However that's a percentage of diameter. Based on prior experience, it would have dropped way too fat of a bullet. Too much to size without deforming the bullet. I want it for 300 BO/ 7.62x39. I cast very hot, and with very hard alloy. If the actual mold diameter is 0.309 I would expect it to drop bullets around 0.308" Add a thou for coating, and I could avoid even having to size. In my experience, the general advice about making your cast bullets 2 thou over nominal diameter causes intermittent feeding issues, and is not necessary for accuracy if you have hard enough alloy, and/or powder coat. This drill rod is a hair oversized anyway, so I can make as many variations as I need until I get the results I want. By far my main goal for this is to make an accurate 300 BO bullet which performs and loads the same as the Hornady Vmax 110. Bullets fatter than 309 do not feed well in all of the barrels I've worked with. 0.308" is better.

I think bullet diameter variance would be related to the alloy used to cast with. RCBS had a Cast Bullet Manual, and it has a section in the beginning describing variance of diameter based on alloy from pure lead to 1:10, to linotype

@@GunFunZS unless you're running a mini 30, you're going to run into problems with that plan