I am having a few misfires with my 646, I use the rimz moonclips and also the metal ones from Brownells. I use the thinner of the two from Brownells.Do you think that the thicker clips would solve my problem?Also have any of you tried the Ranch brand from Midway.They appear to come in only one thickness.I think that most of my problem has been with Blazer Brass ammo, which I understand has hard primers.

I bought one of the last production 646s new, and went round and round with reliabiity.
First, I used the thin clips: wrong! Bought the thicker ones from moonclips.com.
Then I tried putting in lighter springs: wrong! Had to use full-power mainspring with a little tuning.
So now it is nearly 2# heavier than my 686-4 trigger pull, but is smooth and 100% with Fed or Win primers.
I know some people who tolerate an occasional misfire to get a lighter trigger pull, but misfires drive me nuts in practice or a match, and can get me killed in a carry gun.

Hi:
I would sent the Model 646 to the factory to be checked. The problem could be one or more of several problems.
Jimmy

I installed either an Apex or Cylinder & Slide extra long firing pin, a reduced power Wolf mainspring and a 13 lb rebound slide spring in my S&W 646. It functions reliably wth Federal primers.
You should try the extra long firing pin but do not dry fire with the ex long FP.

Start with ths basics. Did you tighten the strain screw? Is it clean under the extractor? Endshake over .003?

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The strain screw is tight, clean under the extractor, and no endshake.

If your running a factory main spring, plus steel clips and are still having issues, then do like said advise and order an extra long firing pin.

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