A good friend passed me a 66-5 missing hammer, trigger, springs, cyl. Latch button. I go grab it tonight, but wanted to see where the best place to get parts would be. I believe this would be a MIM hammer which I'd rather avoid if possible.

Part two of the question, are these easily installable, or should a gunsmith handle these chores?

Thanks,

Michael

A S&W forged hammer will not work in the MIM gun. I'm not sure if the forged S&W triggers will work. The MIM guns have firing pins integrated into the frame whereas the models with forged hammers have the firing pin (nose) riveted to the hammer. Power Custom makes some forged case hardened hammers and triggers that will fit into the MIM guns. Midway USA has some in stock but they are expensive. About $180 for hammer and $120 for a trigger.

Keep in mind that those parts cannot just be "installed" as is.
They will require fitting and adjustment to work properly and safely. No doubt, take it to a qualified gunsmith.

There may be some others on this forum that can provide more info.

While this is a good rule of thumb for older revolvers, OEM replacement parts on the MIM guns (beginning with revision 5 on the models 66, i.e. 66-5) are "drop-in." Indeed, that was the point of implementing metal injection molding: to eliminate the need for hand-fitting and the costly labor associated therewith.

Even most manufacturers of aftermarket forged hammers/triggers for the MIM guns using modern CNC techniques will say "[g]unsmith fitting is recommended but not always necessary." See, e.g. Evolution IV Revolver Hammer Kit from Apex. From experience, this means the part is drop-in, but if you want the action tuned/customized post-install, see a gunsmith.

Good point on the MIM parts!

What are the group's thoughts on sending this old girl back to Smith and Wesson for a rebuild? I don't want them to decide they can't fix it and then offer me a new gun, although I suppose a 21 would be ok...

I checked this morning and it appears that Midway has most if not all of the parts you need. Minor fitting may be required, but is rarely needed, particularly with the use of MIM internals.

You could call and check with S&W about returning the revolver to service. I believe there is a fee for evaluation, as well as an estimate of the total cost provided prior to the work being started. The only problems are the long wait periods associated with repair at the current time, and the other perhaps debatable issue, their "hit and miss" Customer Service these days.

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Ret. LE, FA Instr, S&W Armorer

I would buy the parts and install them and see if it worked. The hammer and trigger are the only thing you listed that are fitted. The double action fly might need adjusted.

Everygunpart.com has a 64-5 now for $250. which would get you some extra parts. Piece at a time Does add up, but probably not to $250 although you could resell the barrel and cylinder.

A wanted to buy on here might get you what you need. I bought a stainless 357 cylinder from a member her cheap and he told me he had a bunch of other stuff too