Oreo sent me the following reply. I am thinking that I will move forward with the .401 spec mold.
"Hey there GrumpyGramps,
I am the honcho for the group buy. Regarding your request for the larger size, I believe the .401" spec will be cut at .4015" and maybe even a tad bigger. Would that be sufficient? Is the .401" size a deal breaker for you?
I reduced the caliber spec by a thousandth for this production run in an effort to get molds that drop closer to my original spec of 403 (with lube groove.) MiHec cuts cavities big and I'm trying to compensate for that. Since MiHec is the one cutting the molds I'm in no position to guarantee what the result will be but I thought you should know why it is what it is. You can always lap a mold out a thousandth but a mold cut too big will always be that way, and .404"gg/.403"pc is too big for most folks, I think."