My wife has complained forever that I have a screw loose. Turns out she was right.

I bought this 639 from a local fellow whose dad just didn't think he could handle it anymore. Dad bought it new. Each time I tighten the screw holding the decocker lever, it backs itself out after a magazine or two. Is this a job for Loctite? If so, which color do you recommend?

Thanks!

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Some insight here - 2nd Gen safety lever question

Excellent. Thank you sir.

On the 645 I purchased 2nd hand, someone replaced both levers with ones from a 4506. While it may not be original, It looks good, & no loose screw to worry about. GARY

As pictured, your 639 doesn't have the original screw. Two different screws were in use by S&W, the slotted screw in your picture is not either. Numrich may have one that is a better fit.

In the original, it was either Philipps, or Allen head. I forget which came first. GARY.

Thanks to all of you. Yes, I now recognize the original owner must have had this problem and eventually lost the screw.

Once I order the correct screw, do I go with blue or red?

Blue so it's easier to remove later for cleaning or replacement of any small parts.

The Philips screw was first, the allen head came next and eventually both were improved with the final method which is on all 3rd Gens where the paddle fits in a slot and is retained by a spring and plunger.

The 3rd and final revision is certainly the best and your pistol will accept it as an upgrade -BUT- you'd need to source and buy the entire unit (looks like a drum, contained in the slide) and that might be cost prohibitive.

The allen screw head is certainly a much better looking option than the philip's head. That looks like a metal screw that has no place on a handgun. The slotted screw you have currently may not work (maybe it will?) but it sure looks better than the original philip's head screw.

S&W dropped the ball with that silly screw.

Any thoughts about putting a tiny lock washer under the screw head?

I wouldn't, simply because the design hasn't used one.

If the screw you have now properly fits the threads and will snug down, I would simply use that screw and add the loc-tite. Blue loc-tite is the stuff I use for screw threads. The actual LIQUID in the tube is blue... the silly little tube is red and that causes confusion.

The factory screw is 8x32. If you are unable to find a factory replacement, and if you like the appearance of the hex head screws, the screws listed below could be shortened slightly to function properly...at least for the stainless variant. These screws can be found on line and at various outlets, not just Home Depot. Come in 1/2" and 3/8".

Crown Bolt #8-32 x 1/2 in. Internal Hex Button-Head Cap Screws (2-Pack)-69678 - The Home Depot

Crown Bolt #8-32 x 3/8 in. Internal Hex Button-Head Cap Screws (2-Pack)-02338 - The Home Depot

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Ret. LE, FA Instr, S&W Armorer

Thanks everyone for your help. $1 well spent.

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Blue Loctite.


Be sure to degrease the screw and the threaded hole. I usually take a Q-Tip and remove the cotton fluff and then use it to clean any "stuff" out of the threaded hole. Then Blue Loctite and screw it down tight. That's been holding mine for years. Loctite doesn't work worth a darn if the surfaces have any grease on them.


Good luck.


FWIW . . . HTH

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1st Signal Brigade, RVN '70

I couldn't figure out any way to clean down in the frame but did use alcohol on the screw threads. I went with blue and hope that'll hold.

Fortunately, the $1 from that Big Orange Home Improvement Store bought me two screws.

I have the 3906, but I've always wanted a 639. The company always hyped the supposed improvements of the newer model, but they cut more corners than improving them. I loved the wood grips and the polished slide and frame. The 3906's frame is unpolished and is finished in such a way that it can't be buffed and polished easily.

It appears your gun doesn't have the wood grips. I love my 659 more than my 5906, but I have both and enjoy them. It's a great gun and should last forever.

Wood grips?

Who knew?

Smith & Wesson Factory Grips Assembly S&W 745 - MPN: 165380000

Was that the intended link? 745 stocks won't fit a 639.

39-2/52/439/539/639 stocks are the same.

Got 645 in my head for some reason - getting old is awful.