Sorry to bump this necro-thread, but I just wanted to add my 2 cents wirth.
I picked up this brand new 617 a couple days back, smoothed up the action and commenced to do some dry firing. After maybe 1,000 pulls I noticed that I was indeed dinging the cylinder. Again, this is a NIB S&W 617, with all factory parts & pieces...
No more dry firing WITHOUT a snap cap/spent shell for me!