Walther TPH misfires

I have a Walther TPH pistol in .22lr that fails to fire about 10% the time; it's a little worse from DA, but it also misfires from SA. The firing pin indentations on the rim are all quite faint on all cases, fired or not. I added a Wolfe extra power mainspring, which did exactly nothing and the firing pin is moving free and has proper travel in the firing pin tunnel. The slide is fully forward and nothing seems wo be interfering with the fall of the hammer. I'm not too familiar with .22lr semi-auto pistols, but this sounds like excessive headspace. With a non locked breech semi-auto, is it worth getting a .22 headspace gauge to test for excessive headspace? I read that the German TPH pistols were tightly headspaced and would occasionally slam-fire; the USA/Interarms guns (mine) were made with greater headspace resulting in no slam-fires but poor reliability. I don't expect this tiny pocket pistol to be 100% reliable, but I would like it to work most of the time. Any suggestions would be welcome. Thanks.

I just did a TPH that had a D/A misfire problem. Check the hammer travel in DA mode, it should be less than the single action travel, about 70 to 80% or so. If it is short stroking, look at the right side of the hammer for a worn sear edge, it will be a very small defect, but will render the DA hammer strike ineffective. Replaced the hammer and cured the problem. Make sure the safety is rotating ALL the way out of the way..

Look at the chamber mouth, check for a divot in the face where the firing pin has dented the area under pin strike(dry firing damage). If all the obvious mechanical causes can be eliminated, then look to the ammo, This crap that is out there these days will drive you to drink. I have a customer that had misfire problems with a Smith&Wesson mod 41, all it was was poor ammo, big box syore loss leader stuff.

Lastly, be Very careful of the small, fragile piece of aluminium at the mag release when disassembling and reassembling, you crack it, and its toast. I had to make a special milling jig to repair one. Its a pain..,,...

Thanks SOF. The chamber mouth has a definate divot from the firing pin which has to be from dry firing. Should I just stick a $20 replacement firing pin in it and see if this fixes the SA misfire (or do I need to replace/repair the barrel-which looks like a bear to remove without damaging the frame>)? I'll check the issues that you mention for the DA misfires. Thanks for the info..

Check the length of the firing pin and to see if there are any firing pin strikes on the chamber walls. Also check the tip of the firing pin as well. And check the firing pin spring. The firing pin itself may need some work after impacting the chamber walls,As far as the length of the firing pin may have actually been shortened by hitting the chamber walls, In any event every thng in or on the rim fire bolt should be given a through cleaning.Some of the ruger 10/22 firing pins can be lengthened by tapping on them with a small hammer as a case in point.

It sounds like the slide may be standing off the breech. This happens when the slide does not come completely forward and contact the breech face. What happens is that the lower portion of the hammer strikes the lower portion of the slide instead of flat on the back of the slide. If this happens most of the energy of the hammer is used up driving the slide to battery before the firing pin is struck. It usually causes intermittent firing. One time it hits hard and fires and the next time it barely dimples the case.

You can test for this by loading a full mag with the ammo that has been giving trouble and firing one shot, lowering the gun and carefully trying to push the slide farther forward. Continue this procedure through a few mags one shot and try, shot and try. Pushing the slide home every time manually should confirm that this is the problem.

If you find the slide can be pushed forward any noticeable amount try to ascertain whats hanging it up.

If you have a dry fire dimple on the face of the barrel it may have peened an edge over into the chamber and is dragging on the cartridge. Iron the chamber or use a chamber reamer to clean it up. Do not polish 22 chambers with Chinese boring bars, especially if one side is rolled or peened over. It will bell them.

The second common cause is the extractor. Pull it out and clean and deburr it. Polish the leading edge where it rolls over the cartridge rim to a mirror finish.

Heavy extractor spring. Make sure you have a replacement first. Begin cutting a coil at a time off and see if the problem is corrected.

Extractor slot plugged with lead and carbon. Clean with a dental pic.

Ammo shaving. Some ammo such as truncated cone bullets will shave a sliver off the bullet and it will be caught between the rim of the case and the chamber mouth holding the rim back. Polish the mouth of the chamber with a cone shaped felt bob and matchless, rouge or 555. Try different ammo.

Heavy wax bullets. Bullet lube can cause the bullet to stick in the chamber. Clean with lacquer thinner and use better ammo.

Weak return spring. Not coming to full battery. Replace spring.

High riding mag. Mag lips dragging on the bottom of the slide. Refit mag or change.

Bastardized mag spring. Some people change out the mag springs with heavier ones or put blocks under the spring and the following cartridge drags the slide. Replace mag.

aap2, any results on the Fix? Kinda curious if you figured out the problem.

Results add to the knowledge base.