I heard that the poly rifleing works like shallow conventional rifleing. It grabs the hard jacket and imparts a spin. Whether the softer lead bullets eapand too much and cause friction or not enough and doesn't spin, I don't know. I doubt if this is a safety issue.
Ace sporting goods Washington PA. acefirearms.com They have brand new a 686+ 5" unfluted for around $659. It is mislabeled as a 686, but says 7 shot on the tag. Wish I had an extra $700. Just gave them a good bit for my JM625.