J frame misfires

[Binky Tremain]

18 years ago I had a trigger job done on my 940...every now and then I would get a light hit, but it has progressed into no hits. I dont even see the firing pin after pulling the trigger.

What the heck has happened? And how do I fix it? Really like this gun (but then I have fallen in love with snubbies).

 

[robertrwalsh]

Could be a lot of things unfortunately. If you have shot it a lot, the spring could be tired. If you are really getting no firing pin strike at all there could be an timing problem, especially if it started happening suddently. Are you sure the cylinder is lining up? Could even be a short, broken or otherwise buggered up hammer nose / firing pin.

Just for the hell of it MAKE SURE IT IS EMPTY, hold it up to the light sideways and look between the rear of the cylinder and and the frame, then pull and hold back the trigger. See if the firing pin is sticking out. It should be easily visible. If it's not, something is significantly wrong.

 

[Binky Tremain]

I tried that, and the firing pin does not pop out at all. If I push up on the hammer spring and pull the trigger, the firing pin becomes visible.

 

[500 Magnum Nut]

I guess your gun has the firing pin in the frame. Pull the trigger and hold it all the way down. Look at the firing pin, if it's not there you need a new one, yours might be chipped.

I can't think of any other cause why the pin would not stick thru. You do have the original main spring in the gun? If not put a new one in.

 

[David Sinko]

Funny you should mention this... I have a 940 but mine is the only handgun I own that I have never disassembled. I ordered a spare firing pin and spring from Brownell's just as a precaution in case mine ever broke. Both items were in stock and arrived just today. It looks suspiciously like any other frame mounted firing pin in their newer revolvers. You should remove the sideplate and take a peek at the firing pin. If you have never removed a sideplate before, have somebody who knows how do it for you. Then you'll be able to see if you have a broken firing pin. If it's not the firing pin or spring, then things can get really complicated.

Dave Sinko

 

[WR Moore]

The key to this thread is "18 years ago I had a trigger job done". Replace the mainspring (hammer spring) with a factory new one. The J frame just doesn't have enough hammer weight to play around with a lighter mainspring.

 

[todd51]

Amen Mr. Moore

 

[HEADKNOCKER]

The 940s have a frame mounted firing pin that's different than the ones used in the revolvers nowdays, I know because S&W sent me the wrong one that I replaced several times, It took talking to an older tech who knew that this revolver had a firing pin bushing & cross pin..
It does sound odd to me that pressing up on the mainspring strut makes the firing pin protrude when other wise it wouldn't??
Hopefully you won't get into having to change that type of FP but it can be done with simple hand tools & alot of patience..
I gave a good description a while back to a fellow wanting to change one on his 640 with pics..
I'll give the link of that thread & post the pics here..
http://smith-wessonforum.com/s-w-smithing/108001-advice-firing-pin-bushing-replacement-model-640-a.html
I'd start with a new J Frame mainspring & go from there if it were me..
BTW the FP can be broken & it still function, Just don't hold it upwards when you dryfire or the back half of the pin will fall out into the action.


940 Frame Sideplate Removed + FP Bushing Pin

Broken Firing Pin 940 NOTE: Wrong Newer Style Behind It

Firing Pin Bushing 940

Installing Firing Pin Bushing

My HomeMade Bushing Press

Firing Pin Bushing Installed With New Stainless FP

Broken Firing Pin Small Pic

 

[David Sinko]

OK then, it appears that Brownell's sent me the wrong part. They sent me a newer style firing pin that looks like a MIM part for a newer gun.

From the photos, the firing pin, spring and bushing look a lot like the setup in a Ruger Redhawk. The problem with the Redhawk is the cross pin is polished even with the frame and impossible to remove without a drill press or milling machine, and a lot of patience.

Thanks for the informative pics, Headknocker. My 940 is the only S&W revolver I've owned that does not shoot any screws loose during dry or live fire and the trigger pull is perfect. I've never had any reason to take it apart and look at it, so this is all news to me.

Dave Sinko

 

[HEADKNOCKER]

David don't take that style apart unless it's broken..
I used a 1/8" steel punch & small elf hammer to drive the cross pin out..
I reused the old bushing & used a new cross pin & a brass drift to drive it in so the beveled end wouldn't take any markings..
You have to dry fire the bushing out on a Centennial as you can't get a punch behind the firing pin because of the closed frame design..
I noticed when stoneing the rebound slide & DA Sear on the hammer that the back half of the Firing pin would just fall out, I had never seen this before & after asking around found just a few people who knew what was going on, S&W was helpfull by sending me 5 of the newer style FPs, the ones that are now "Too Long" for drop tests so now thier RARE, but only after talking to the right person & emailing the above pics did I get the right parts, 640s have the same parts BTW..
When I recieved my 940 it had a homemade endshake screw that was hand filed & just looked wrong & had no spring loaded end to it..
So after ordering these parts from S&W I started my dismantel of it to smooth it up a bit by squareing up the DA sear & stoneing the rebound slide smoother..
I can only assume that the broken pin was from the wrong endshake screw or many many dryfires, I don't dryfire my 940 without A-Zoom snap caps in .040" thick moon clip, Just in Case..
I'll also note that the factory Endshake screw has red locktite on it from the factory.. You can see it in one of the pics laying with the other parts..

If I were the OP I would be putting a fresh new mainspring in the gun first & being that only requires the grips to be removed.. And Go From There..
If/When the sideplate is removed I'd remove the hammer & hold the gun upright & touch the back end of the FP to make sure it's not broken
The replacement FP was stainless the original was carbon steel..
I didn't take a pic of the replacement just the one pic of it after install
Gary/Hk