Light pin strikes on auto pistol, cont'd

I hate to re-open this thread, but I have a few suggestions not addressed in the prior one.

quote:Weekender: Posted - 08/03/2009 : 9:38:00 PM
Help! I purchased a 9MM pistol (new) in February. It has been back to the factory twice and had the firing pin replaced and a new extractor. It has also been back to the shop and had the firing pin replaced. At the shop it seems to shoot fine with various ammo. When we go to the range I load 5 rounds in the clip. If the first round goes off then it is more likely to shoot through the clip. When a round fails to fire I can get it to go off (sometimes)by pulling the hammer back and firing it. It will fire fine for a few rounds and then it may have light pin strikes on the next 3 or 4 rounds. Last time out I had 8 light strikes out of about 30 rounds. Any ideas?
Thank you.

. . .

We have tried to shoot American Eagle, Federal, Remington, and Sellier & Bellot through it with the same results. The pin strikes are a little off center but not too bad. It is a PT92. Customer service is thinking that we may not be holding the gun firm enough. I have never had this problem with any other automatic pistol. Someone once questioned whether or not the spring was broken and would not line up at times. Gun has less than 300 rounds through it. On the third time to the factory and been serviced at the shop a few times. Thanks again.
Again, there is simply NO WAY that how you are holding the gun is causing this problem. At worst, "limp wristing" can cause failures to feed, but it shouldn't cause failures to fire. If the added inertia of a firm grip is required for the gun to go off, then the gun design itself is defective. We know that this is not the case for the PT-92.

A truly broken spring somewhere would mean the gun would NEVER fire. . .not inconsistently fire.

Slightly off center firing pin strikes are normal for some guns, and probably aren't the issue here.

While a bad/damaged firing pin could cause this problem, we can assume that since its been replaced twice, the firing pin itself is OK. Since the problem occurs with multiple types of factory ammo, we know its not ammo-related.

Going to first principles, repeated misfires (ie light firing pin strikes) mean some problem occurring in the mechanical chain in between the hammer spring and the primer. And since the gun at least *occasionally* goes off, we know this can't be a major part failure (like a totally broken spring, broken firing pin, etc).

There are multiple possible causes, you'll have to work through this to figure out which (if any) apply:

a. Weak hammer spring isn't generating enough force to consistently ignite the primers. Sometimes you can get this problem with a gun that has had an action or trigger job. Lowering the hammer spring pressure to get a light trigger pull can compromise ignition reliability. I suppose excessive wear to the spring could cause this problem as well (though that's pretty uncommon). In a new pistol, neither of these should be a problem, but its at least possible that your spring is out of spec. Fix here is a new spring.

b. Dirt in firing pin channel or firing pin hole. Any crud in the firing pin channel can variably retard the firing pin movement causing erratic ignition.

c. Burr in firing pin channel (or firing pin hole), or too-small hole.

Same as b, above, and in a new gun, this is a likely culprit.

I had this problem with a pistol and not only would the gun not fire consistently, but the firing pin would actually get stuck in the firing pin hole. Finding the problem took a little while, but once I found it five minutes with some emery paper to take out the burr, and the gun has since run 100%. A too small firing pin hole may also be prone to accumulate dirt, etc.

d. Dirt in chamber, or out of spec chamber (eg burr, etc). Same idea, if the cartridge isn't seating properly and consistently in the chamber, you might get erratic ignition.

f. Dirt/burr in RAILS. This was mentioned in the last thread, but again, if the gun doesn't return 100% to battery after each shot, you could get inconsistent ignition.

There are probably a few other ways this can happen (eg defect in safety, etc) but they're probably pretty unlikely. (And I personally, I wouldn't mess with detail-stripping the safety in a brand new gun like this).

All that said, if you can't figure this one out, with this new gun now having been back to the factory twice, I think it behooves Taurus to give you a new one. A gun with a high misfire rate out of the box with ordinary ammo (particularly ball 9mm) is simply unacceptable.