I shot a match with a heavily used police, then police academy 686 M Stamp and for the first time ever... out of 100 rounds shot, two misfires on the same cylinder using factory Zero 158.

I took the 686 apart and noticed the hammer nose rivet was moving side to side but it had to be hammered out. The hammer nose did feel "springy" while installed (meaning I could feel the spring when moving the HN)

I removed the hammer nose and the little spring to assist the hammer nose is crushed on one end.

Not sure if that little spring is still available, but will it be reliable without the hammer nose spring?

being over 60, I started using cheaters (3.5+) and I am seeing stuff that I have never seen before (HA!)

I had never noticed the lines to the staked in part that retains the cylinder. does that part look ok? It does not move but seeing the lines with the aid of 3.5 magnification has me asking.

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if you're gonna be a bear...

The frame lug staking looks ok.

If you can't find a replacement hammer nose spring, you could probably just reuse the one you have by installing the damaged end point first, placing it down inside the cutout in the nose. The hammer nose spring is not necessary for proper function.
If you re-install, be sure to re-stake the rivet. The rivet should not move after staking.

If you can't source a spring from S&W I can send you one.

If the gun is "well used", you may have some excessive end shake contributing to the misfire problem. Shooting debris inside the cylinder assembly and under/on the extractor can also be a problem.



Carter

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Ret. LE, FA Instr, S&W Armorer

Thanks for the info. Bob Jones tuned this piece after I bought it from the police academy I work for.

That would have been 2009ish.

It’s mainly shot 148 wadcutters after the Jones’ tune with some 158s.

Some years ago the center pin hole on the frame had excessive egg shaping. I waited 2 years for Cylinder and Slide to have me send my 686 in to bushing the center pin hole.

I still have the two misfired rounds. They have pretty good firing pin intentions. I was not able to try and re strike them.

I do have a spare cylinder for this piece just in case.
I keep it clean

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Just a thought, is/was the strain screw all the way in and tight?

MidwayUSA has the N-frame hammer nose, nose spring, and rivet in stock. Numerich and Jack First are also good sources to check out.

This is an Lframe. Not sure if Nframe stuff interchanges.

The strain screw has been backed out a 1/2 turn since I got it from BJones some years ago. I actually checked it after that match with two misfires. It had not moved.

I shot another 50 round match with it afterwards and no issues

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Here was my matches.

The first one I was shooting low at 25 yards (18 rounds) and then encounter the two misfires at the 25 yard stage.

Horrible.

Second match (I was actually shooting make up from the previous months missed match because I had to work)
I am allowed to shoot twice. The sun was hot and glare in my eyes. Same brand and lot of Zero 158 SWC.

The illusive 500 still rained on my parade but oh well, I will take it.

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if you're gonna be a bear...