Misfire Problem

[Unregistered(d)]

I am hoping that someone can help me with a misfire problem that I am having with my new Kadet conversion unit.
            I purchased the kit back in February and have been very impressed with its quality and accuracy. The problem is that I was getting about 4 to 6 misfires per 10 round magazine. It turns out that I still had the round firing pin, so e-mailed my CZ distributor and arranged for a 'chisel' firing pin kit to be sent (new firing pin, rebound spring and retainer plate). The problem is that this is still giving be at least 3 or 4 misfires per magazine. I have tried several different types on ammo, including European stuff, but the firing pin indent seems shallow compared to a friend's Ruger mark II. Interestingly, all of the rounds fire on the second or third pull of the trigger.
            There doesn't appear to be anything wrong with the hammer / frame as I use this with the 9mm slide and never have a misfire problem.
            The rebound spring seemed very stiff and exerted a lot of pre-load on the firing pin, so after getting some advice from a friend that is a mechanical engineer I have tried reducing the overall length of the spring (by compressing and heating it) but this has done nothing to solve the problem.
            The pin moves freely in the slide, but it only protrudes 1 to 2 millimeters past the retaining plate when installed. Could this be part of the problem?
            I would appreciate any advice you can give.
           
            Regards..........AlanB

[SEE ZEE]

AlanB,
           
            I had problems with my kadet misfiring on my 75SA,  installed new firing pin and still had problems.  Purchased heavier hammer spring from Wolff spring and installed it,  this only increased trigger pull slightly but increased the reliabilty greatly.  Hope this helps.
           
           
           
           
           

[Unregistered(d)]

Thanks for the advice, but that hasn't helped the problem.
           
            For some reason the firing pin strike is still very light.
           
            Do you think that it could be a headspacing problem? That could explain why the firing pin is only striking the cartridge softly (if there is excessive headspacing and the cartridge is moving forward when the firing pin hits it.
           
            Any other suggestions? What do you think?

[Unregistered(d)]

I've found that with Fedreal ammo I had a high missfire rate with the 22LR.  However with Remington very few misfires occur.

[gberghane]

I love my KADET, but I went through a lot of grief with misfires in the beginning.  Usually at least 2 rounds in a magazine of 10 would fail to fire.  Tried every brand of ammo that I could find.  It didn't matter!  Then my dealer had CZ replaced the firing pin with the new chisel tipped one.  No noticeable improvement.  I cut some coils off the firing pin return spring.  No improvement.  Then I had a machinist turn down the end of the firing pin collar by .020 to allow the pin to extend back farther for the hammer to get a longer stroke on it.  Some help, but still not perfect.
           
            Then I looked closely at the fit of the slide as it closed against the back end of the barrel.  Bingo!  There was enough metal left at the back of the slide in the corners to prevent it from solidly and squarely locking up against the barrel.  If it didn't lock up tight, misfire happened.  A little work with a small file and my Dremel and the lockup was fine.  No more misfires.
           
            Hope this helps.
           
            By the way, mine was purchased as a conversion when I got the CZ-75, which is an excellent 9mm.