Still getting misfires with Model 18 after reaming

[Tom S.]

First move, put the factory hammer spring back in and tighten the screw down. Then test. If misfires are still occurring shim the cylinder back .003 and test fire again. If misfires still occur, try a different brand of ammo.

A longer firing pin might work but as far as I know, no one makes one for S&W rimfire revolvers. The frame mounted pin could be modified, but should be done by a smith who knows what they are doing.

 

[max503]

Lots of good stuff here. The things you learn almost make it worth having a problem.

 

[max503]

If you installed a Wolff "Power rib" mainspring and didn't use an extra length strain screw that is probably the problem. Wolff doesn't tell you ) (last I looked) that their power rib spring MUST have a longer than standard strain screw!

You may have other issues, but this is a big one.

I called them today and this is what they told me. No big deal. Wish I knew this when I ordered the spring.

 

[SweetMK]

Are you shooting single action, or double action??

I would try single action, and if it still misfires, I would pull the hammer back, then jiggle the cylinder to make sure the cylinder is correctly aligned,,, BEFORE firing.

Out of time can happen just as easily as not having enough hammer force.