Success! Thanks, to all!! A 750 gr bullet sized down to .729 at 1050 is the ticket. I pulled apart 4 of the H&H rounds, and resized the bullet, then reloaded in the brass cases to 1050, and it works. Can't send any targets, as the ranges were full for what I was doing, but shooting at a 6" rock at 100m, I can bust it in half, then hit one of the halves- this twice in a row, and to the sights! SB mould on order.

Seems the recoil factor is at play here. When I reduced velocity the crossing got worse, the opposite of what I expected. I think that at this low velocity, the recoil is more of a factor than barrel dwell time. Anyhow, thanks to all, and Mike, that is a great idea for the Chrono! Seems that no matter how well I protected the thing, a wad would still fly out at the wrong time!
Thanks, All Doug