Mister C, a few years ago, I ordered some of the rosin powder from Brownells to try in my barrel vise blocks. It probably helped, but I never used it again. It fused together and to the blocks and barrel like concrete. It was a project just getting it off. The cornstarch is a surprise, but lapping compound somehow makes me uneasy. I understand how it works, but the 3M just sounds better, and wouldn't risk etching a scope body.
Informative thread.
Thanks, Tom