After firing about 200 rounds in my model 66, the screw on my cylinder release thumbpiece works loose. I bought this revolver used, but like new with the exception of the screw. The previous owner must have had the same problem. Can the old screw simply be taken out and replaced with a new one? If I install a new screw, should I use loc tite when I install it?

The thumb release screw is not really a screw but a cap screw. If you remove it and replace it with a new one, it should work, but the male threads on the release may also be bunged up.

I do believe however, that the cap screw is made of a lesser strength material than the male threads on the release itself so I think that you should be okay in replacement.

DO NOT Loc-Tite it unless you use the removable type. Even then I have heard that is hard to get off if you wish to remove the cap screw again....something about applying heat for removal.

I have used a small dab of RTV Silicone to fix backing out screws before. It can be removed without any trouble what so ever and re-applied when the screw is replaced. (I used to use that trick while driving off-road in a Baja Bug, worked extremely well there too.)

If I were you, I think I might try this trick before replacement.

I needed a new screw for the thumbpiece on my 642 a while back. I got it from MidwayUSA.com for cheap.. I actually got a few extra just so I didn't feel I was wasting an online purchase....

I'm trying to find the link for you as I speak.. er type

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- The Federalist #46 -

OH! Thumbpiece NUT.

MidwayUSA - Smith & Wesson Thumbpiece Nut S&W 60, 63, 64, 65, 66, 67, 242, 296, 610, 617, 624, 625, 627, 629, 631, 632, 637, 638, 640, 642, 648, 649

is this what you need?

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- The Federalist #46 -

The problem is you are not tightening the thumbpiece nut tight enough.
Just a little more will generally stop this from happening. Replacing the nut with a new one won't help if you don't tighten it any more than the one already in the gun. Very little Blue Loc-Tite will help but isn't necessary if the nut is simply adequately tightened. The same goes for the sideplate screws. Bet if you check those you will find them loose too.

Thanks USAF385. That's exactly what I need.

Alk8944, the Thumbpiece NUT was kinda "boogered up" by the previous owner. I guess they were trying to keep it tight also, but didn't use a good hollow ground screwdriver tip. I really want it for cosmetic reasons and a new screw/nut should tighten up and stay put. Also, the side plate screws are all snug.

A little finger nail polish will do the job.

+1 on the nail polish. Works great.

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John