K-Rod
Add 2% tin to your COWWs and the cast with the alloy at 725 degrees. Keep the mould hot, pour the alloy into the each cavity separately and leave a good sprue over each cavity. If using a dipper get the alloy into the mould quickly as it cools off faster than we think.
I'll bet the 429667 will cast to nominal diameter. I have a standing offer to test Lyman moulds that supposedly cast "undersize". If you try the above and it doesn't cast to nominal I'll ask you send the mould to me. I will test it and if it does cast to nominal I will send it back with full details on what was done. I do no "magic" to get Lyman moulds to cast to at least nominal diameter. I follow standard casting procedures as out lined in Lyman's and other casting manuals. If the mould does not cast to nominal diameter I will buy it from you, if you want, for what you paid for it plus the shipping to me. You can then get another or order a custom mould. If you want it back to then send to Lyman no problem, I pay the shipping back to you.
PM me if you want to give that a try.
Larry Gibson