I took my 66 to the range yesterday. Shot perfect until the end. I was almost done with my box (50) of 38 specials. I shot 6 357’s. It started out of nowhere and quit shooting double action. It would shoot single action only! I would pull the trigger and all it would do is rotate the cylinder and the hammer block would drop at full trigger pull.
I took off the side plate and there’s a long thin bar with an “S” on it in front of the hammer. It wasn’t popping out to engage the trigger for double action. I tried to clean it and cycled the action several times and it started working again.
I am considering taking to a gunsmith,but I would like more info.
Thanks.

Welcome to the FORUM! It kinda makes you sick inside when something like that happens. I have a 29-2 at the gunsmith now with similar problems.
As many guns as I have owned over the years, it is the 1st 1 that needed "work" that I could not do. You should post in the S&W Smithing section for more responses. Hope everything works out for you. Bob

First, you need to know what you are looking at when you remove the sideplate... those parts are mostly hand fitted and what you call a gizmo, I may call a gadget... So, until we know we are both talking about the same thing, it is hard to determine the cause of your problem. The hammer block does sit loose but in a defined slot within and is rarely a cause of such a problem. It doesn’t engage anything. I would suspect several things but would strongly encourage you to take it to a gunsmith or send it to the factory for a proper repair. If you had your location in your profile, someone could be close by that would offer assistance.

Do you have a history on this gun? If bought used, it's possible that a former owner did or unsuccessfully had done a trigger job on it. Whatever, it sounds like something in the internals is on the ragged edge to cause double action to fail intermittently. As others have suggested, take it to a qualified gunsmith and have it checked out. Guns are expected to work 100%. Accept nothing less.

My location is Louisville ky. The gun was bought in 1990 from the original owner in very new condition. I believe from the serial it is a 1976. I will take a picture of the part in question. But it has not been fired much. It was shot in once 2007 (me and my grandpa) and this time in 2018 (by myself) It was my grandpas gun now it’s mine.

Here is the photos of the pistol. I will take a picture of the part in question.

Attached Images

	937B9558-8380-4E8C-A304-E7CAE3DC4A76.jpg (65.0 KB, 93 views)
	0CDEC30A-F8C8-4EC2-AC56-7F66769F18EA.jpg (65.6 KB, 86 views)

The long narrow piece with the yellow arrow pointing directly on it is the one. It wouldn’t pop out and engage to allow double action shooting.

Attached Images

AABF6959-24C7-43CF-B2E7-587E78C8821D.jpg (93.1 KB, 194 views)

Last thing on my mind. I read somehwere a long time ago that the early model 66’s has problems during long periods of double action shooting. I don’t remember the specifics but the guy said they remedied the problems in the first dash models.

A.K.A. the double-action sear. Considering the age of the gun I imagine it just got held up with some gunk. As you've noticed it's spring-loaded and needs to pop out every time for the trigger to catch it. Just make sure your cleaning got into the area where it rides and you should be good for another 42 years. Don't over-do oiling it either; for revolver innards I like a dusting of graphite.

__________________
TEAM DNF

This.

Most people don't take their DAs apart for a real cleaning (or have it done) very often and problems like this is the result.

The good news is nothing is broken.

This might help:

S means Stainless Steel
If cycling the action with the side plate off "BE SURE TO RELEASE THE MAIN SPRING TENSION, OR SEVERE DAMAGE CAN OCCUR TO YOUR PISTOL"

Have you pulled the hammer out to check for a problem with the sear?

No I have not removed anything except the side plate. Thanks for the info about not cycling with the side plate off. I ordered some snap caps. I want to cycle a few hundred times to really make sure it’s ok. Then go back to the range. If it keeps working then I’m happy. I am opening carrying this revolver every day so I am depending on it.

Give the internals a good cleaning
Walt

So I gave the internals a good cleaning. Bought some snap caps and cycled the double action many times. No more problems!

Good work
Walt

My first guess: Someone way back used WD40 and it has gummed up enough to prevent the spring from forcing the piece out so it can be engaged by the trigger.

Spray it out with Gun Scrubber or similar, and lube sparingly with proper gun oil, such as Break Free.

I was shooting 357 yesterday and one time i couldn’t pull the trigger SA. It was cocked but it would not fall. I had to fan the hammer back then pull the trigger and then after that it was fine.