Didn't get a chance to post before family activities, but I'm back.
First go with the Ace bullets, fresh and soft from the oven, answered the plain base vs boat tail question...still yawing horribly and not grouping at all.
Ok, so I buggared the neck tension on all these loads, was still using the .331" neck bushing for the soft military brass and my pig-getting loads, which outs these RP necks at .304" ID. Swapped to .337" to get about .3085" and just kiss the necks with my custom .3085" powder-thru die (thanks Waco for the stainless steel round bar scraps).
So after fixing that I loaded ten more just the same and got a noticeably better group, but still with wild flyers and yawing.
Thinking something was still amiss with the launch, I went back and changed two things for the last ten: Switched to CCI 300 primers and seated the bullets out about .025" more to engage the lands a little more. Much better group, down to 2" or so, and much reduced yawing. Then I was out of time. I wonder how the Lee bullets from the lapped mould will do with the pistol primers? I solved the mystery now of why the yawing showed up....I somehow forgot the pistol primer thing and started using large rifle again.