I have a J frame in 22 LR that is having lots of misfires. The brand or type of ammo is not the issue. It misfires using bulk ammo or higher priced target rounds.
I had thought to change the firing pin which I did , to no effect . Had fun doing it though and learned something about wrenching on my guns, so thats a win, but I still have a misfire problem.
Many of you folks are far more experienced than I .
Is my next move replacing the main spring , which is a coil spring in this model, and the hammer and return springs.
This pistol is about 44 years old , so some spring replacements may be expected.
Thanks !

If you have not already done so I would flush the internals out thoroughly with aerosol brake cleaner (after removing the stocks) and lightly re-lubricate. After this, if it still doesn't fire every time I would probably look for a professional diagnosis before changing out more parts.

__________________
Alan
SWCA LM 2023, SWHF 220

What he said. Also, be sure to scrub the heck out of the cylinders . If the round sits out just a few thousandths, it can absorb energy of the hammer blow and cause FTF.

As for springs, it's not unheard of that a weak mainspring could be the cause. That is an easy and cheap swap. The trigger return / rebound spring has nothing to do with hammer force so it can be left alone. If you still have issues after cleaning and changing the mainspring, it needs professional care.

__________________
Dave

Dirt and debris, especially on and under the extractor, and end shake, or improper rear gauge/headspace are the two most prevalent causes.

Take a close look at the extractor itself...with a magnifier. Build up of shooting debris and lubricants on top of and under the extractor can cause problems, especially in rimfire guns.

The rear gauge or headspace is also critical, and should measure .008" - .010" after a thorough soaking and cleaning of all of the components. (especially the cylinder assembly)

__________________
Ret. LE, FA Instr, S&W Armorer

Posts #2, 3, and 4 provide every bit of information necessary.

I have owned several S&W .22 rimfire revolvers over the past 40-odd years, and every one of them exhibited at least one of the conditions described.

Well this one has plenty of end shake.
Not ridiculous , but more than some I own.
I'll seriously clean the cylinder and replace the mainspring and see what I get.
Thanks to all .

How tight are the chambers? Are the cartridges inserted to solidly bottom out? Tight chambers and less than positive cartridge insertion can cause misfires. The cartridge, not fully seated will be driven forward and the firing pin impact is absorbed. Have you tried to second strike the round and did it go off?

S&W .22 RF revolvers have historically had over tight chambers. Polishing, scrubbing, etc can help, but only reaming the chambers with a standard finishing reamer will fix the problem.

__________________
H Richard
SWCA1967 SWHF244

Coil springs usually have a long life , do you think some weaker springs could have been installed by a former owner to get a lighter trigger pull.
Sometimes the lighter spring swapping will give failure to fires .
Gary

Plenty of endshake can cause misfires in any revolver, since the firing pin strike is moving the weight of the entire cylinder forward before it can deliver a solid blow to the primer. Look at all the things mentioned above, there's some very sage advice in this thread. Sometimes it's a combination of problems, rather than just one thing.

If you decide to try to fix the endshake issue, suitable yoke shims are available here:

S&W J Frame Shim Kit


Be sure to order the correct j-frame shims, as the "rimfire" yoke design is a bit different from the center-fire j-frame yoke.

__________________
Ret. LE, FA Instr, S&W Armorer

I actually bought this gun new in '74 , so no , no tinkering.

I use a 30 caliber brush on the cylinders of my 40 year-old Model 34. It would be no big deal to change the main spring.
I think mine might need it too.

Does it misfire in both single and double action or only in double?

I only shoot it double action. Haven't checked to see about single action.

Checking the single action can often provide useful information.

After scrubbing and shimming for end shake, number the chambers with a Sharpie pen and see if there are only certain chambers with FTF.

If there are, hone all the chambers.

If not then I would focus on the hammer spring, You buy the appropriate size at the hardware store, Use dikes or a hacksaw to cut a slot in the washer so you can slip them one at a time under the bottom of the mainspring w/o dismounting it or removing from the gun, to test.

If that fixes it, you can leave them or buy a new spring. For a stiffer factory spring you can use one from the 317 Airlight .22 but you won't like the trigger pull. Then there's always aftermarket springs.

__________________
Jim
S&WCA #819

I was at the range today and ran about 100 rounds through the pistol. Single and double action.
Most of the misfires were in double action. All actually , as I remember .
Last week after reading the posts I got some frame shims and moved the hammer .002 to the right as I was seeing some abrasion on the hammer.
Apart from that I cleaned the heck out of the chambers and ejector . Not filthy by any means but it couldn't hurt.
Much improved but not perfect.
I haven't found cylinder shims yet that fit.
I think that would sort things out entirely .
Don't think I need to ream the cylinders the rounds chamber easily , at least when its totally clean.

Thanks , ordered some shims and installed the .002 trigger shim and saw significant improvement .

Good luck.

I also bought a new M34 in the 1970s. I also had trouble with misfires in double action. I changed the main spring, I cleaned the chambers, under the star, etc. I did just about everything that has been mentioned in this thread. I finally sold it, some time in the 1990s.

__________________
John 3:16
WAR EAGLE!