So a quick update. I received my 627 with a 9mm cylinder fitted ( actually can accommodate 9mm, 38 super, 356 tsw, 9x23) about 45 days ago. Just didn?t have the time to get to the range.
Took it to the range yesterday, accuracy was a non issue. It shot POA, which surprised me. I tried 147 Federals, 124 Speers, and 115 Tula crap. The 147 Federal shot best, but all were fine.
Did experience some light primer strikes. At home found the mainspring screw backed out ~2 turns. After tightening it, and shooting it again this morning, it ran like a top.
Am really looking forward to shooting some matches with it.
So to recap, my 627 Pro now has 2 cylinders- the original for 357/ 38s and a the new cylinder chambered for 9mm ( and the others listed above). Am really happy with this set up.