I finally had a chance to take my Chiappa 22 upper out to the range.  I didn't run a lot of rounds through it but I was having light primer strikes.  It cycled fine with the Federal bulk ammo but the indentations on the cases were very light.  It might just need to have a couple of hundred rounds run through it but it was 1 round out of every 5 or 6 rounds that would fail to go fire.  I have it on a YHM lower receiver with a Stag Arms lpk with a curved hammer.  I was thinking that shaving the tail off the hammer might get better primer strikes.  Anyone have any suggestions?

Thanks!

If you're getting light strikes 1 in 5 or 6, it may clear up after 500 to 1000 rounds.
Making a speed hammer out of the one you have will give more momentum and
may well help. Heavier Hammer Spring if you are using other than Mil Spec. I've
never had good luck with light springs.


Dave

I took it out again yesterday and was still having problems with light strikes.  I got light strikes with the Chiappa upper about 12 times out of 25rds with Federal bulk ammo.  I had my other 22LR set up (M261 kit in a dedicated upper and lower) and switched the two uppers and lowers and the M261 kit was running flawless on both lowers.  The Chiappa upper would not work on either so I know it's the upper.  I'm going focus on the firing pin and firing pin spring and see if that will work.

Here's what the firing pin looks like.  Could the firing pin spring be too strong?

Take out the bolt and push the firing pin through the bolt and see if it is long enough to
strike a good dent in the rim of the ammo, if it looks long enough then check the firing pin hole
for dirt or anything that will slow down the pin, if all looks good then play with the spring or send it back to the maker
I dont know the size of your spring but you can try this.
I have played with a inkpen springs on a few 22 kits and have had good results
without modifying the stock spring, inkpen springs are easy to find, cheap and
no big loss if you cut it too short.

+1 to what Redtazdog said....He's very good at getting things to run.

It may just be the picture but the spring does look pretty stout.

Yes, it can.  Your local Ace Hardware might have one of the same diameter at a lower weight.  I did have to change out my friend's firing pin spring for that exact reason.

The other day I tried that.  I was pointing it at the berm and firing as I looked over the ejection port to see if it was closing all the way.  It looked like it was but I have torn the upper down and have been doing the polishing tips from this thread: http://www.ar15.com/forums/topic.html?b=2&f=282&t=173040.  I still think it's the firing pin spring since it's very stiff.  I found a replacement from a ball point pin as suggested.  It might be a while before I get to shoot it again but I'll try to post an update.  

I have seen a few different sizes of ink pen springs so you may want to shop for springs before
you go out to test again that way you wont need to make several trips to test.
Don't forget to bring something to cut the springs shorter if needed like I did
We will be waiting to hear if the change or mod with the springs work so we can
praise you for fixing your problem

I'm interested to see how it turns out also.  I have a Chiappa upper also.  Don't bet on it smoothing out after a 1,000 rounds.  I have tried multiple types of bulk ammo, and many boxes of the "premium" ammo.  Nothing seems to work for mine.  I've only had a few mags that run flawlessly out of over 1,000 rounds (probably closer to 1,500).  I have cleaned it well and tried to run it wet, dry, and everything in between with CLP.  Nothing works.  I had it out on Labor Day and my buddy and I were trying to run a brick of shells thru it.  What a joke.  Ftf, fte, stove piping, casings get jammed into the chamber, and light primer strikes.  You name it, I had it.  It would fire anywhere from 1 to 5 rounds before something would happen.  I think I had one streak where I made it through half the mag.  I have also tried the upper on 4 different lowers (2 home brews and 2 factory built lowers (Spike's & Bushmaster)).

I emailed Chiappa directly, but I haven't heard back.  I'm hoping they can give me some pointers on fixing this, or send me a replacement.  I don't even enjoy shooting it because it acts more like a single shot rather than an auto.  I may go ahead and try some of the tips above with the springs if I don't hear back from Chiappa soon.

I too have a Chiappa upper, however, I haven't experienced any types of failure in mine to date.  I'm not quite sure how many rounds I have through it though.  I've run a bunch of Remington bulk through it.  I am curious to see what the fix is for this, that way if I do start seeing failures, I know what to do.

Also make sure there is nothing in the firing pin channel. Dirt, or a burr.
I see Retazdog already said that.

Sorry for the lack of updates on this upper.  My wife had surgery at the end of July so I've been playing Mr. Mom for the last month.  Things are back to normal now so hopefully I can get this upper to the range to test out.

Been there. My wife fell down the basement steps and broke her right wrist and ankle over the winter. Now she knows I can cook

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Fixxed it for you