Home Forums Hunting & Shooting Handguns Need help & suggestions on a S&W revolver.

Friend of mine picked up a four screw model 17 at a local gun show. Gun shoots great in single action mode, but only goes off part time in double action. Tried different ammo with the same results. He replaced the hammer spring and strain screw because it looked like someone had ground on the spring trying to lighten it. Still did not fire every time in double action. Looking close at the firing pin it looks like it's flattened out slightly so I suggested me get a hold of S&W and order a new one. He calls S&W and the lady tells him "I would suggest you contact Jack First or Numrich Arms". What the heck. You mean you can't order a firing pin from S&W anymore? I told him to contact Brownell's, but he went on vacation and hasn't called them yet. Told him I would look into it to try and help. Any of you guys experience anything along these lines? Have also read that the new 17's use MIM parts so I don't know if they are compatible with the older 17's. Any help or suggestions would be greatly appreciated. Thank you. BCM

Someone weakened the hammer spring to improve the trigger pull. Also check to see if that little screw at the base, and in front, of the grip frame is screwed in all the way.

If the firing pin is peened and the rear face is mushroomed you can take it out and spin it in a drill against a file or stone to take the flare out of it and then put a bevel on the edge to stop it from happening again.

If not I’d call Cylinder and Slide and talk to them about an over length pin.

S&W gave you the right contacts, Jack First is the first place I'd go.

And S&W doesn't stock parts for something that was discontinued 25 years ago. MIM parts are not interchangeable with older S&W's. When they went to MIM, they made massive engineering changes to just about every inch of the revolvers.

So first off you looking at a revolver that has been messed with. Other than main spring and strain screw you have to wonder what else has been played around with. Guessing this gun and firing pin is the result of lots of dry firing so you may well need a a new one. But rimfires like this have a in-frame firing pin so there may be other issues. Peened firing pins are a no go

Have you tried different ammo and are the results the same ? 22 ammo is famous for quality problems many of which are rim thickness which equates to headspace issues.

On S&W revolvers the SA hammer fall is a bit longer and hits a few oz. heavier opposed to the DA hammer fall. So check it out both ways it will probably fire on SA.

Firing pin protrusion is critical on rimfires and many center fires. I can’t pull the measurement number off the top of my head but I’d check this out as this alone will cause your problem

End shake on older revolvers will affect ignition especially rimfires. I can’t explain the best way to correct this without seeing the gun but if you have excessive end shake that could be a problem

Make sure your mainspring is factory or aftermarket correct. The strain screw should also be factory then trimmed if you know what you’re doing. Either way once the gun is running up to par and the spring is tuned you can blue Loctite it to hold it. But best to work with various ammo brands and find what works for you.

Rick

If it was my revolver I'd change the main spring. Make sure it is the factory weight spring. The lightweight springs in the Wolfe kit are often not heavy enough for consistent ignition. You can get them from Midway etc. and they are cheap and easy to install. Plenty of how to videos on Youtube.

Reading comprehension seems to be lacking here. He did change the mainspring, and then he found a damaged firing pin.

And the strain screw as well. Reading for many here is tough, apparently.

Many "armchair gunsmiths" here in too much of a rush to offer their "expert" opinion to bother with reading or comprehending.

Gun Geek, EdM and gunswizard,,, THANK YOU. BCM

And “Tried different ammo with the same results”…

If the suggestions here fail to resolve your issue you might check in with the great people on the S&W forum. They have helped me several times. Good luck solving the issue. I love my K 22's they are great guns.

Not to mention he said it worked just fine SA, that it was DA where the problem lay.

Another thing I have seen done to S&W revolver is after adjusting the strain screw aftermarket stocks won't fit, so they shorten the strain screw. You might try inserting a shim between the strain screw and the hammer spring to find out if the additional tension helps the problem.

Thanks HeavyLoad and Dirtdoctor. Dirtdoctor I even read where a guy used a spent primer cup to use as a shim between the strain screw and the spring. That method might get you through in a pinch, but I would not leave it like that permanently. Thanks once again all you guys. See ya, BCM

If the shim fixes the problem, purchase a new strain screw and replace the old one.

It's most likely the adjustment screw for the hammer main spring

Get your flameproof suit on.

I’d take bets on it.