P7M8 malfunction - help sought

[YVK]

I've posted the same request on PCT boards as well. Just trying to reach a larger audience...

Gents, I am having problems with my P7M8.

About two months ago I had a situation when I had slide stuck several times in it's rearmost position. This occurred while I was trying to lock slide back manually, but during live fire gun cycled normally.

We've had discussion about this here http://www.parkcitiestactical.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=10;t=01.

I've not been able to pinpoint the problem, but I was sure that it wasn't due to dirty gas chamber. To the end, I chose not to clean or lube the gun before the next session, during which I proceeded to fire 50 rounds without any issues. Again, I couldn't reproduce the malfunction.

After that session, I cleaned and lubed the gun, including thorough gas chamber clean-up. The following range session consisted of 100 trouble-free rounds, and no problems during manual slide lock back.

However, today, during 50 rounds range session, the slide hung up again, except it was during live fire. Similar to the first time, it wasn't a lockback as the cocker wouldn't release it forward. Slide simply stops in it's rearmost position and requires a slap to go forward.

I can't figure it out. It is not a gas chamber. I've not changed my maintenance routine, except that in last year I've used a dab of grease mixed with on rails (as opposed to oil only in my early years owning this gun). The only difference in usage is that recently I've been using manual slide lock very often; I wonder If I've done something that caused it to interfere with slide movement. Visually, though, everything looks fine.

Anybody knows anything about this - please let me know.

[custom60]

The link to your discussion at PCT doesn't work for me, so I have no idea what has already been addressed. Those guys/gals over there are pretty knowledgeable on the P7 variants so I don't know if I have any other insight but..................? I would revisit the gas cylinder/piston. If you know for certain that the cylinder is in fact without carbon residue, especially the rear of the cylinder then inspect it for defect. Sometimes either piece can become worn, warped, damaged so that they can bind, even though they are "clean." Also, if other tools such as a drill bit are used to clean the gas tube it can score the surface of the cylinder. It might not cause a problem when the pistol is clean but after a few rounds enough carbon or tiny shavings from jacketed bullets (of course you're not using lead?) might enter the tube and cause a problem. Have you tried a new recoil spring? Maybe the spring is worn enough that it can't overcome the normal friction associated with the P7 piston/gas system. I would suggest you call Trussville and ask for "Travis", their gunsmith and run it by him. He's really good and helpful. Don't waste your time explaining your problem to the other reps, they'll just tell you to send the pistol in. Good luck!

[Danner]

Your gas tube isn't clean enough.

A little pile of soot builds up directly below the gas port in the barrel. If you take a tiny pen light, you can actually look into the gas tube and see it.

You need to find a cleaning regimen that gets that taken care of. Brush, scraper, solvent, ammo choice all affect this.

[CZ-75]

Certainly, everyone's instinct about the gas tube are well founded.... But it is possible that there is a broken part elsewhere that could cause an intermittant failure.

I would inspect the drop safety catch and spring to be sure it looks Ok. Also inspect the firing pin assembly and bushing to see if anything looks cracked or broken. Finaly, take the grip panels off, and look at the internals closely and see if anything looks odd.

You could also contact Bruce Gray and see if he will offer up any insight. he used to compete with a P7 that he had custom made.

[H&K 4 LIFE]

I had the same exact thing happen to me with my newly repaired M8. The slide didn't lock back far enough for the squeeze cocker to engage it and release the slide, but it was no where near the closed posistion either. It did require a "slap" on the rear of the slide to get the gun back into action.

I feel this was due to a dirty gas cylinder and dirty WWB ammo. I cleaned the gas tube throughly, switched to Blazer Brass for ammo, and used Breakfree for lube instead of Hoppes oil. Since doing this the pistol has fired 100 trouble free rounds and will be firing another 100rnds. today. :)

Perhaps your gas cylinder needs a scraping. It could have so much "plaque" on the inside of the gas tube that the brush just isn't cutting through it. Also, when in doubt, try some different ammo.

Hope this helps.

[YVK]

I had the same exact thing happen to me with my newly repaired M8. The slide didn't lock back far enough for the squeeze cocker to engage it and release the slide, but it was no where near the closed posistion either. It did require a "slap" on the rear of the slide to get the gun back into action.

Hope this helps.

H&K4, I am not sure if we've had the same malfunction. The slide on my pistol travels all the way back - beyond the point of normal slide lock - so there is no more rearward motion possible. It then gets stuck at that point, and requires a slap to move forward. Is this what you had?

Gents, I appreciate your efforts to help. I know that the gas cylinder is a "usual suspect", but I doubt it in my case. I bought this gun brand new in 2004 and I have had 7200 trouble-free rounds before this happened. My maintenance routine has not changed a lot - in first year I cleaned it after each range session; 2 years ago this gun went without issues through 600+ rounds "no cleaning trial" and I increased cleaning interval to 200-250 rounds. I shoot only factory ammo, Blazer Brass and regular Blazer lately. Every cleaning involves soaking piston and cylinder with solvent, scraping and brushing it with factory tools, and finishing off with q-tips. The last string of malfunctions happened within 150 rounds after such cleaning.
Based on above, it is hard for me to buy into foul gas chamber theory. It is also hard to imagine that this pistol requires more meticulous and frequent maintenance that I've already given it.

I called Trussville - you can only leave a voice message now. The automated reply stated they'll called back tomorrow. Does anybody know a direct extension # for Travis? Or his last name?