P7PSP Failure to Cock

[cek]

I've posted this question on the Cult of the P7, but am doing it here as well to get more eyeballs.

I recently purchased a NIB P7PSP that had been imported by PW ARMs. Since purchasing it I have put about 300 rounds through it and have encountered an increasing number of “failure to cock” failures. To the point where during my last outing it was failing to cock almost every 2-3 shots.



It goes like this:

• Full magazine of factory (American 115gr FMJ, Fiocci 115gr FMJ, Corbon 115gr) or reloads (115g Rainier Total Copper Jacket with 4.3gr, 4.5gr, or 4.7gr Win 231).
• Squeeze-cock, pull trigger, bang
• Keep squeezing, pull trigger, bang
• Keep squeezing, pull trigger, bang
• Keep squeezing, pull trigger, _nothing_
• Release the squeeze cocker, re-squeeze, striker sticks out the back. Pull trigger. Bang.
• Keep squeezing, pull trigger, bang
• Release the squeeze cocker, re-squeeze, striker sticks out the back. Pull trigger. Bang.
• And so on...

Sometimes I can fire a whole magazine without a failure, but as I put more and more rounds through the gun the problem appears to be getting worse.

I have _very_ carefully verified that this is not ‘operator error’. That is, I am 100% certain that I am completely holding the squeeze-cocker tight between shots.

Photos of the internals:














Have other P7 owners or experts ever seen or heard of a problem like this?

[68fan]

Sorry that I can't help with your P7 issue, but I had to say that I read about your dad's contest win (from the link in your sig)-- pretty cool story! :)

[AviatorDave]

Squeeze-cock, pull trigger, bang
Keep squeezing, pull trigger, bang
Keep squeezing, pull trigger, bang
Keep squeezing, pull trigger, _nothing_ (Is the striker still protruding from the rear at this point?)
Release the squeeze cocker, re-squeeze, striker sticks out the back. Pull trigger. Bang.
Keep squeezing, pull trigger, bang (Did you mean "no bang?" Otherwise, why would you release the cocking lever in the next step? And... same as above wrt the striker)
Release the squeeze cocker, re-squeeze, striker sticks out the back. Pull trigger. Bang.
And so on...

[cek]

Squeeze-cock, pull trigger, bang
Keep squeezing, pull trigger, bang
Keep squeezing, pull trigger, bang
Keep squeezing, pull trigger, _nothing_ (Is the striker still protruding from the rear at this point?)
No.
Release the squeeze cocker, re-squeeze, striker sticks out the back. Pull trigger. Bang.
Keep squeezing, pull trigger, bang (Did you mean "no bang?" Otherwise, why would you release the cocking lever in the next step? And... same as above wrt the striker)
No. Each time it did NOT go bang, the striker never stuck out, and I had to "re-cock" to get it to fire again.
Release the squeeze cocker, re-squeeze, striker sticks out the back. Pull trigger. Bang.
And so on...

Put another way:

The failure occurs when the gun is cocked (I'm squeezing the grip) and I pull the trigger. The gun goes bang, the round ejects, a new one is chambered, but the striker is NOT protruding. I have to release my sqeeze of the grip and re-squeeze it to engage the striker.

[G3Kurz]

[QUOTE=cek

First off, GREAT post cek. Makes sit easy to understand your issue.

From your description it appears the firing pin is not being retained rearward in the cocked position occassionally when the slide returns into battery, but not every time. Therefore I doubt your sear lever spring is the issue. All parts in the pistol look correct, in in the proper positions (you have New Style Drop Safety Parts BTW - a good thing). So it seems to me that it could be in the gas system or your ammo. If the gas cylinder is fouled it might cause the slide not to recoil fully. Does the slide move "roughly" or smoothly? Clean that very well with the cylinder scrapper, brush and some strong copper solvent left standing overnight. Ammo - you mentioned a wide assortment of ammo. If you have some underpowered rounds mixed in the mag, OR you limp wrist the pistol on occassion, it maybe be such that not enough recoil impulse and/or resistance on the pistol to allow the slide to travel fully rearward on the previous shot. When this happens the sear lever cannot engage and hold back the firing pin. Thus the slide goes forward and the firing pin is uncocked. Usually however this causes a failure to eject or feed first.

I must ask are you holding the squeeze cocker fully back for each shot? I have seen more than one P7 shooter unknowingly release the cocking lever during recoil and then resqueeze after thinking they had it held back all along. That would cause the problem as well of course.

I am thinking a worn disconnector too but look into these other areas first.

1. Throughly clean the gas system
2. Try factory loaded ammo 115-124 grain only
3. Use a strong two handed grip
4. Insure you hold the cocking lever back
5. All of the above

Good luck.

G3Kurz

[tquieng]

clean the gas piston chamber with the chamber cleaning tool from midway for $24 or so --the chamber needs to have all the carbon out and clean.

[cek]

Thanks for the thoughtful ideas G3Kurz.

1. Throughly clean the gas system

It is clean. I clean it after every firing and the gun does not have enough rounds through it for it to have fouled anyway. I have shined a light up the piston and verified it is clean. I'm anal about gun cleaning. Note in the pictures above I did not clean the gun prior to posting because I wanted to capture what it looked like after shooting.

2. Try factory loaded ammo 115-124 grain only

I only tried the reloaded ammo in an effort to diagnose this problem. Of the 300 rounds i've shot with this gun, maybe 20 of them were with reloads. All ammo I use is 115gr.

3. Use a strong two handed grip

I was trained in shooting 1911s. I use a death grip.

4. Insure you hold the cocking lever back

Note he slide does move somewhat roughly. My 1911's, Hi-Power, & ig P228 are silky smooth. This gun (and my HK45C) have a feel of more "metal on metal" but not in a way that caused me to really consider it. The gun has no problem ejecting brass 10-15feet, but I know that the slide action has basically nothing to do with ejection on a P7 due to the design of the chamber.

But it seems unlikely that the slide is not moving far enough/fast enough to cock the striker. I can manually cock it by sliding the slide back and I only have to move the slide about 1cm for it to cock. Hold the cocker, dry-fire, and then pull slightly on the slide about 1cm and the striker pops out and stays out.

[H&K 4 LIFE]

Wow, this is a head scratcher.

The only time I had anything remotely like this happen was when my FP bushing broke. Once dry fired and upon releasing then re-squeezing the cocking lever the FP did not always recock. It would sometimes, but not always. However, it always recocked during live fire due to rearward movement of the slide. In addition, a broken sear lever will result in no cocking of the firing pin at all.

However, your pictures have ruled out a broken FP bushing as well as the broken sear lever.

Under "Failures to Fire", Section 5.3.1 of the P7M13 armourers manual it also suggests disengament of the firing pin block (drop safety catch) spring as being the cause. http://www.hkp7.com/PDF/p7-techmanual.pdf

It looks as if your drop safety catch/spring is assembled in the slide properly. My only idea (besides what has already been mentioned) is you can remove the drop safety catch and spring and test fire the pistol this way. That way you can rule out a weak drop safety spring, that is sometimes causing the drop safety to fail to disengage, as being the cause of the malfunction.

Best of luck. :)

[Big Dave S.]

It is most likely a weak firing pin return spring. I would recommend disassembling the firing pin, stretch out the firing pin return spring to strengthen the force, reassemble and try again. If that takes care of it, order a new firing pin return spring and install it. Please let us know what it turns out to be, as we can all learn from these posts.

[coto20]

[QUOTE=G3Kurz;831090][QUOTE=cek

All parts in the pistol look correct, in in the proper positions (you have New Style Drop Safety Parts BTW - a good thing).
Good luck.

G3Kurz[/QUOTE]

G3Kurz, I picked up on the comment above on a "NEW" style drop saftey parts. I have two of the T25 CDNN PSPs and an M8. I am going to send one for refinishing and also to Springfield for his work. Are the new parts an advised change? What issue did they correct? Was the change made before after a specific date code?

Thanks for any updates on this topic!