If memory serves me, 1996 is when they first started making the internal lock on the 686. Smith stopped making the 586 sometime in the 90s, so I'm not sure if it was before or after the introduction of the lock. It might be possible that the 586 was never made with an internal lock. That's also around the time that Smith started introducing MIM internal parts. Some have said that they're not up to the quality that they used to be and others have said they have no problems at all. My opinion, if I were looking to buy another Smith revolver, I would prefer one of the older models with no lock and no MIM parts. That's just because I like the quality and craftsmanship of the older Smith revolvers. But if I didn't have a choice or couldn't find what I was looking for, I'd end up going for one of the new models. Unless you're shooting thousands and thousands of rounds per year, I doubt you would see much difference in the quality of the internals as far as wear and tear. But the 586 isnt' exactly a difficult to locate gun. Gun shows and shops in my area usually have a decent selection. So in that case, I'd buy one of the older ones just because there is still a decent supply of them. Older Smith revolvers seem to be significantly increasing in value, so that's another added bonus.
