old thread but worth updating, because nowhere on the net does anyone cover all the issues with this gun in detail. My wife bought a J22 new about 25 years ago. We still have it. It's a good snake/tackle box/glovebox gun, but has feed/extract/eject issues, and also slam fire/chain fire issues, as the slide breech bolt face wears.
1. the barrel chamber opening protrudes from the barrel frame collar, this eventually pounds into the slide breech face, causing loss of headspace. The gun will start to chain fire i.e. 2-3 shots from one trigger pull, or slam fire i.e. fire a round when it's chambered hard from a fresh full clip. The gun will fire from the bolt face hitting the case head, without using the firing pin. Like hitting a 22 bullet case head with a flat hammer, eventually it may go off anyway. The fix is, file down the chamber face flush with the frame collar, to restore headspace.
2. as the slide is alumi-zinc alloy and relatively soft, as it gets pounded in from use, the slide closes too far FORWARD on the frame, causing the extractor claw to ride up on the barrel collar, and move out to the right side. Then the claw is not engaging the cartridge case rim. The fix is, using a small file, file the groove in the right side of the barrel further forward on the barrel and frame, so the extractor can grab the case head upon closing the slide. The extractor should not move outward to the left at all, when a round is chambered. If it does, file the groove more.
3. As the slide wears, it keeps slamming into the barrel/frame upon closing over time, the slide bends upward at the ejection port, and to the right- the ejection port is the weak point, being it's cut out. The left side is a solid rail, so it is stronger. What this does is, cause the slide to progressively bend to the right and upwards, at the snout. It can only go so far before contacting the barrel, but on a heavily worn J22, you can see air space between the right side of the frame and the slide, and it's bulged there. This leads to:
4. The firing pin channel on the bottom of the slide, also bends to the right, with the rest of the slide- this causes the channel to rub on the inside upper feed lips of the clip, spreading them apart with time. You can tell a worn slide by looking underneath it, the firing pin channel will have a slight curve to one side as it approaches the bolt face area. This spreads the clip rails apart wider, causing the shells to pop up too high while feeding. Eventually the rounds stick up so high when trying to feed, the shell misses the chamber opening, and the front nose of the cartridge (the bullet nose) hits above the chamber, jamming the gun. This is an additional problem, to the extractor not gripping the cartridge, so even if you fix the extractor problem, it still may not feed, until you close up the clip rails. If you close them up too tight, they will grab the firing pin channel in the slide, and be hard to work the slide. So just close them up a little bit, and tap the feed lips down slightly, so the cartridges don't climb too high and miss the chamber.
5. The main large slide spring, is probably too strong for the average 22 LR standard velocity round. I have not experimented yet, but am going to progressively cut coils from the spring, until standard velocity rounds will fire and eject without jamming. A spring that is too strong, will not allow a std. velocity round to fully work the slide and eject the spent shell, as the force of the std. vel. round isn't enough to fully expose the ejector blade. It all has to work together.
The guns can be serviced per above, and used long term. The fix is, keep an extra slide or 2, and an extra clip or 2. When a slide becomes so worn it can no longer be tweaked, change the slide and start over again.
by what I can read and glean on the clips, the plastic replacement clips feed much better than the metal clips- that's because plastic won't bend and stay there like metal, and is smoother than metal with less friction. If you can get a plastic clip, buy one.
soft potmetal guns typically develop problems like this, the 1900 era little pocket pistols also had bent frames, etc. that would give over time and cause the guns not to function.
If someone made a mild steel slide for a J22 it would last forever. Let me just add, I'm not a cheap SOB that won't buy a good firearm, I have rifles and pistols worth $2000 and up. I see the Jennings as a challenge as to how much life can be squeezed from such a cheap pistol. They are cheap fun, and if you are the tinkering type with some mechanical aptitude, they are easy to fix and work on. Just be careful, because a J22 that is worn, can be a dangerous firearm. Never carry one with a shell in the chamber.