Trigger Job On A S&w 640

G

Glockzilla

Inactive
I just received a new Dremel for Christmas and am interested in doing a trigger job on my S&W 640 (38 +P, SS, DAO, etc.). Nothing fancy, just smoothing the action, perhaps putting a mirror finish on the trigger itself. I am not interested in changing or clipping springs. Can anyone suggest the best bit to do the job? I am pretty knowledgeable in firearms disassembly, so tearing the action down is no problem.

Being that this gun is my off-duty/BUG, I might even work on the exterior, removing any sharp areas along the frame, front and back of the cylinder, etc. I might even lightly chamfer the chambers. I'm not talking serious metal removal, just smoothing things out.

Can anyone offer any hints or suggestions to make this project go 'smoothly'. Comments are appreciated!
 
I suggest you leave the Dremel tool for cutting nails into-like they do in the TV commercial.......
the single most important piece of lockwork which will greatly aid in your desired effect of having a smooth operating revolver is the bottom of the rebound housing.
Those came from the factory with a mirror finish---many years ago.
A very hard Arkansas oil stone used in conjunction with the same type of oil which machinist use in their hot cutting jobs will do very well. Just begin the time consuming process of rubbing back and forth on the bottom part and when you can see yourself in it--then it is ready for service.
The ramp on the trigger which engages the hammer pawl should not be touched unless you have experience in that area of operation. That angle is very precise in a Smith and Wesson revolver. More than likely your gun is operating very well and I urge you to not touch those particular parts unless you want to remove the pin, spring and pawl and polish the bottom of the pawl and in such a manner which will not change the ramp angle-even a very minute amount.
If you decide to remove any of the trigger rebound spring then you should make sure you flatten the end of the coil and do so without bending it.
Don Mallard
 
The best thing that you can do as far as improving the action on your J frame, is to polish the bottom of the rebound slide and install a Wolf spring kit. Leave the Dremel Tool for other chores...7th
 
I agree with the others - don't dremel your gun. For an improved trigger I suggest dry firing. It will smooth the trigger and strengthen your shooting hand. My S&W 642 has fired about 1000 rounds and about 2000 dry fire strokes over the last 2 years. Everyone who shoots it asks me who did the trigger job.
 
I agree with pointshooter, unless there is a real problem in need of repair. A trigger job is, basically, accelerated wear. Dry firing does the same thing eventually, and no one can argue that you modified your carry gun and made it "unsafe."
 
Since your gun is DAO, don't worry about changing angles (not that you should).

It really doesn't matter that much since you WILL NOT be engaging the single action "ledge" on the hammer (few thousandths off and it won't hold), though you don't want the hammer to drop before it reaches max DA travel for reliability of ignition.
I doubt you even have a SA ledge on a centennial internal hammer.

Hard ark. stones are good, but so are a few passes of 1000 grit sand paper and a Dremel felt polishing tip
thereafter with jeweler's rouge, followed by a felt wheel w/ no rouge. Did this to a Ebel watch I nicked, which is more the than the price of a SIG 210 and finished to a finer degree on the outside than any gun is on the inside. Mirror finish, not just shiny.

However, 70-80% of an action job is the springs. Change at least the rebound spring. DA strikes can be unreliable with a light mainspring. Try it, though.

Heavily modify these suggestions on SA or SA/DA guns.
 
SW Trigger

Don't touch any of the faces on the trigger/sear/hammer as they will not improve trigger action but will destroy the parts. These are factory fitted items. Also, don't take the trigger out as polishing the side will do little to improve trigger action and it is hard to take in and out. The small hand is fragile and people often torque the spring when removing/replacing the trigger. If you polish the hammer sides, go lightly as you don't want to go through the hardened surface.

The best way to smooth the trigger is to polish the rubbing surfaces of the rebound slide (break over the sharp edges) and use a very good lube like Tetra lube on all sufaces (especially sear/hammer). Install a reduced power spring set from Wolff and you will be all set/
 
remember that the trigger and hammer are not stainless (unless they changed recently), they are regular (case hardened) pieces that were "flash chromed" to give them that "white" look...the chrome is very thin.

having said that...

i have had all of my wheelgun actions tuned, which included aligning the cylinder and polishing all contact points.

i think the best use of your dremel might be in taking down the serrations and rounding the face of the trigger (smoother contact) and knocking down (beveling) the edges of the cylinder release and hammer (make your thumb happy) :D
 
Its been a while since S&W hard chromed the triggers and hammers. They're case hardened now.

It isn't that hard to get the trigger OUT, the problem is getting it back in since you must fight the rebound spring, which must be compressed in situ with a punch to allow it to snap back in, then must withdraw the punch while still compressing the spring.

Polishing with a Dremel must remove almost zero metal. If I'd do it to a watch that runs a couple thou ( didn't pay that, though) and I can see my
reflection in the bezel and the engraved numerals are still distinct, there can't be too much wrong w/ it. There can't be a much more obvious test of efficacy.

Better than polishing the sides of the hammer and the inside of the sideplate and frame is to buy bushings (teflon?) that insulate the hammer and the frame and sideplate from each other. Try Brownell's.

Maybe Cylinder & Slide makes a roller hammer & trigger kit for the J-frame cenntenials, but it would probably be $175+ like their others. The existence of these kits also contravenes the idea that the relationship between hammer and sear is that exact in a DAO revolver.

Again the main danger in home gunsmithing your S&W is not the DA action, but the SA. As long as you don't reduce the potential energy that inheres in the hammer at max travel (just before release) by reducing the length of the sear face of the trigger this should be OK.

The price I paid to come by my beliefs is one ruined hammer. DO NOT monkey with the SA of a S&W beyond light polishing. It still shot well as a DAO.
 
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