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P7M8 problem at the range

3720 Views 15 Replies 9 Participants Last post by  jpgeorge
Need advice!

I went to the range with my P7M8 and had problems after about 150 rounds. At first, the slide wasn't smooth. After a few more rounds, the slide kept getting stuck and it was next to impossible to cock . It became unusable until I cleaned up the cylinder!

It really worries me cuz everybody is saying how reliable it's supposed to be.

Does anybody experience a slight hitch about half an inch back when pulling the slide? I didn't notice this when I first bought mine, but I did notice it prior to that day in the range when it had problems.
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Without actually looking at the gun and experiencing what was going on, it's hard to say. But, judging from your symptoms, it sounded like the gas cylinder really needed a good scrubbing with the carbon tool that Hk provides with these guns. P7's are VERY reliable, but they are a machine and will fail if some steps aren't taken to clean it ever now and then. Carbon build up that leads to failure is usually in the hundreds of rounds.

The slide is not supposed to be hard to pull back or anything. Sounds like it just needed a good cleaning.
All of the P7 series guns need to have their gas cylinders cleaned often. If you do that it will function flawlessly.
Two questions.... First, what type of ammo did you use? Make sure that they are actual jacketed rounds. You can't use led or copper washed bullets. Second, how much and what kind of oil did you have on the gas piston? Use oil very sparingly. If it's very dirty ammo, it will foul up the piston very quickly. It almost turns to mud then gets baked on the piston.
Check the slide take-down button on the rear left of the slide. If it gets sticky it can cause the slide to bind about 1/2" into its rearward travel. Ditto the drop safety catch as well, I believe. Clean and lube these parts as well.
Thanks for the suggestions.

I used 115gr FMJ rounds from a local manufacturer here (not in the US). What are "copper washed bullets"? As for the oil I use, the cleaning kit I have only says "gun oil". The brand is outers. I'm pretty sure I wiped most of the oil clean out of the cyliner, but I'll check again the next time around.

Why is it that I've read a lot of comments online that say not to bother cleaning the cylinder? They say it works better that way or something.

I was actually suspecting the slide retainer too, but I don't really know what to clean up here. I'm not experienced with gun maintenance at all. The sides of the slide retainer look decently clean, and the under portion of the slide seems clean too. What am I missing?

So the slide should really be velvet smooth throughout the pull, right? For mine, when I replace the slide without the spring, I can see the slide riding higher (ever so slightly) on the receiver after pulling half an inch.
Clean your gas tube

When I got my P7 I experienced the same thing. Dirty ammo makes things worse, but the gas cylinder is probably your problem.
What has worked very well for me is to avoid any fluid lubricant in the gas cylinder or on the gas piston. I use a dry Teflon aerosol, Elmer's Slide-All. Nothing for crud to adhere to/ Same on the firing pin and bushing assembly and in the chamber and barrel bore itself.
Thanks. I'm gonna give the cylinder a good scrub with some q-tips.

But can anyone please try placing the slide onto the receiver without the recoil spring and checking to see if the slide is velvet smooth or not? It's really bothering me that mine isn't. I really don't wanna wear down my slide retainer or anything!
My slide is "velvet smooth" on my c-grade PSP however I have experienced your same problem on two trips to the range. After around 150 rounds the slide gets really stiff and a round will FTE. A quick splash of oil works as an immediate fix until I can get home for a thorough cleaning.

In my case it's obviously because the slide is so dirty I can barely rack it with my hands. It doesn't bother me seeing as how we'll never fire 150 rounds in a defensive situation and the old PSP works perfectly up until then.
I have experienced a very similar problem. Best you head over to the Cultists:;f=10

Just do a search for 'slide stuck' or similar, and you'll see you're not alone. 150 rounds is not that uncommon for this kind of problem to materialize, though it is rather often.

First, check if you're not accidentally hitting the disassembly button while the gun cycles, that might just get your slide stuck. Although, I do not think I've heard of this happening with a P7M8, as this was mostly an issue with older P7s with raised disassembly button. Since you say the slide doesn't move smoothly even before it gets stuck, that means that is has to be an issue with the gas piston/cylinder.

Cleaning is the word. Make sure you don't use LNR or copper-coated ammunition in a P7M8. Then, check with different ammo, see if there's any variation in when the problem occurs. If it's an older gun, you could check the dimensions of the gas cylinder and gas piston, and inspect the gas cylinder for any visible wear. I've heard, and seen, that over time a groove can and will form opposite the gas port This might just lead to the gas piston getting stuck in this area, though I haven't heard of this happen. Wear on the piston is usually easy to identify, if there's carbon residue, preferably baked on, further aft than the first two piston rings, it's perhaps time to change the piston. And, of course, check if the gas port is free, I use a bent paper clip for that purpose.

Then there's the question of how do you clean the cylinder? As it sounds like there's a fair amount of buildup somewhere in there, it might be a good idea to let it soak in solvent for a while, and then use the piston scraper that comes with the gun to clean it out. After that, I'd use a bronze brush fitting the piston (think it was .270 off the top of my head) and scrub it. It is important to check if there isn't any builup at the bottom (or back, whatever) of the piston, which can be hard to see. Repeat until it works nicely again. Finally wipe it clean with q-tips. Again, make sure the gas port is not blocked. As for oiling the cylinder/piston, I always shoot mine dry.

That's about all I can think of. Heh, sorry for the lenghty post, but it breaks my heart to see a P7 sitting idle.
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I ran my PSP through its paces the other day with about 100 rounds, or so. No problems at all, other than the heat. I keep the cylinder and piston as clean as possible on both my PSP and P7M8. I use Breakfree CLP on the cylinder cleaning brush after running the reamer through it. I then clean the residue with cotton swabs until they come up reasonably clean. I also use Breakfree for general lubricaiton on all my pistols. Never have a problem.
Thanks for the recommendation, guys. I think I can definitely handle the problem with my cylinder being very dirty now. I definitely have to buy a better lubricant for the cylinder.

It's not getting stuck anymore after I cleaned out the cylinder, or at least not yet. The problem is only that it seems to "ride" over something briefly at half an inch from the beginning when I pull the slide back. It's not really a big resistance, but I can definitely feel it if I pay attention and slowly pull the slide back and release.
You may actually be feeling the disconnector. If you look above the right grip panel with the slide off you can see it sticking up. It rides in a groove in the slide.
Try some "Gun Butter"; I use it after using Break Free CLP and find that its lubricant properties, especially in higher heat environments are exceptional.
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