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Discussion Starter · #1 ·
After much study, I landed my desire upon the P17. After a long hunt I got not just one, but two! However, I get many (3 per magazine no matter what ammo) failures to feed at the range. Super clean, well oiled, good, high velocity ammo. I watched this video:
and inspected my gun and yep...loads of friction. Check out these pics and advise
me on fine sanding it down or contact Keltek. By the way, the unused one in the closet (never been racked) has the same friction wear.

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Mine has rubbing marks on the slide and top of the chamber also. However, I isolated the problem on my P17 to the breach chamber. My 22LR ammo has extremely sooty powder residue. Since the P17 action is blowback, the shell case is moving back while it is still burning/spewing powder and that residue coats the area the shell inserts into. Eventually, that causes the round to get stuck before full insertion and stops the slide short. It is worse with extra sooty rounds I have like Remington Golden Bullets. CCI and cleaner rounds can go a lot longer before starting to stick because they are much cleaner.
If I brush out the breach every magazine (15 or 16, without even removing the slide) there is no feed or firing issues.
Also, mine went in to Kel-Tec for repair (had a round rupture). They replaced the bolt (had a crack on the face) and polished the feed ramp. Cycled better but not perfect. I went to cleaner ammo and can shoot 6 magazines before any issues. Brush it out and all is well again. I also polished the chamber and that helps reduce the soot buildup.

Trigw
 

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Discussion Starter · #3 ·
Mine has rubbing marks on the slide and top of the chamber also. However, I isolated the problem on my P17 to the breach chamber. My 22LR ammo has extremely sooty powder residue. Since the P17 action is blowback, the shell case is moving back while it is still burning/spewing powder and that residue coats the area the shell inserts into. Eventually, that causes the round to get stuck before full insertion and stops the slide short. It is worse with extra sooty rounds I have like Remington Golden Bullets. CCI and cleaner rounds can go a lot longer before starting to stick because they are much cleaner.
If I brush out the breach every magazine (15 or 16, without even removing the slide) there is no feed or firing issues.
Also, mine went in to Kel-Tec for repair (had a round rupture). They replaced the bolt (had a crack on the face) and polished the feed ramp. Cycled better but not perfect. I went to cleaner ammo and can shoot 6 magazines before any issues. Brush it out and all is well again. I also polished the chamber and that helps reduce the soot buildup.

Trigw
Where/what exactly is the "breach chamber?"
When you say "cleaner ammo" what kind exactly.
Everything you said makes perfect sense except it has failure to feeds at the beginning of range trip as well. Yes, it does get worse as the rounds go through, confirming what you said, but what about at the beginning? The friction I mentioned?
 

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The breach chamber, as I call it, is the area of the barrel where the cartridge slides into.
My experience with ammunition shows that some brands/versions leave a lot of fine powdery residue after the gunpowder is burned. Some leave very little. 22LR seems to be the worse, I believe due to the qualities of the actual powder and the fact 22LR rimfire semi-automatic (i.e. P17) firearms tend to be blowback designs. In blowback designs the cartridge case begins to move without delay once fired. That means that the cartridge may still have gunpowder burning or gasses/vapor/debris expelled from the case during the case ejection cycle. That debris get "sprayed" in the breach, chamber, bolt, trigger system and other exposed areas. That is sometimes referred to as fouling.
Non-blowback designs, like many center fire cartridge firearms, have a mechanical delay to allow much of the burning gunpowder or gasses/vapor/debris to exit the muzzle end of the barrel. That reduces the amount of fouling.

As for which 22LR ammunition brands are cleaner (less fouling), CCI seems to be much cleaner than my Remington Golden Bullets. I have only used those and Federal Match. Federal has not been as clean as CCI but much cleaner than the Remington Golden Bullets.

An example happened to me many years ago. I was using my semi-automatic shotgun (centerfire). After a few rounds the shells started ejecting with visible smoke being expelled from them, as well as debris. That had never happened before and recoil felt very harsh. It was so bad, that it left black on my face and others near me complained about being sprayed with "powder". Took the the shotgun to a gunsmith that found the locking/delay mechanism had failed and allowed the spent cartridge to eject too early, "like blowback". Repaired under warranty BTW.

Trigw
 

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This is what happens when you engineer a firearm with tolerances that are too tight. Make it a bit sloppy and it'll run with no problems, just look at the difference between an AK and an AR15. The AK model was built a bit sloppy on purpose, and it has superior reliability.
 

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Where/what exactly is the "breach chamber?"
I think he's referring to the top of the 'trunnion', part 105. That's the part rubbing on the slide, causing friction. Could have made the trunnion a bit shorter for clearance, or mill a few thousands off the underside of the slide to prevent contact.

...at least, that's how I understand it. I may be wrong.

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