Picked up a 63-4. Went to the range yesterday, single action worked fine.
Double action had several misfires. Seemed like the firing pin was hitting as hard as the fired ones. At least 2 misfired a cylinder, different cylinder
misfires. Cleaned it real good , went back to range today , better but still
had some misfires. Any help appreciated. I was using CCI mini mags.

I was going ot say it was ammo related until I saw that you’re using CCI Mini Mags.

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Old Cop
LEO (Ret.)

If new, contact S&W, they made need to look it over. If used, someone may have tried to make the double action lighter by swapping springs around. Lighter strikes in double action, but not single, is one of the signs of a weak spring.

thanks for the replies