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I have a Mk iii hunter that I am getting quite a few misfires with it, I have been having this problem since the gun was new. I have polished the firing pin, it was very rough and sticky the first time I looked at it, I have also replaced the hammer, sear, trigger and extractor. The bolt also is not locking every time the magazine is empty. Should I replace the firing pin also the firing pin spring? Is there any thing else that I should replace?

Thanks
Ed

et-lynch wrote:I have a Mk iii hunter that I am getting quite a few misfires with it, I have been having this problem since the gun was new. I have polished the firing pin, it was very rough and sticky the first time I looked at it, I have also replaced the hammer, sear, trigger and extractor. The bolt also is not locking every time the magazine is empty. Should I replace the firing pin also the firing pin spring? Is there any thing else that I should replace?

Thanks
Ed

What ammo are you using? Remington Golden Bullet has a high incidence of FTF in my experience.

Have you tried different brands to see if it makes any difference?

I'm sorry I forgot to post the ammo, I am using the bulk 550 federal.

Ed

In misfires, are you referring to light hammer strikes? I always get a couple from the fed bulk pack, but most fire on the second try.

On the misfires it can be caused by the bolt not going into full battery. Make sure the breach face and the barrel is free of powder residue. 22 ammo is dirty and you will get a build up on the faces. I use a plastic scraper to scrape the barrel/breach area clean.

The bolt not locking back indicates the bolt may not be going back far enough or the mag is not kicking the lock up. Does it happen with both mags or just one. Check for burrs in the magazine tubes against the follower.

Some times they will fire the second time you try them, other times they won't. The face on the bolt and barrel are clean, I made sure of that.

Ed

Another thing to check is the chamber. Some ammo leaves a fouling ring in the chamber that causes the rounds to not seat fully. This leaves the rims off of the chamber face just enough to absorb the firing pin hit without pinching it satisfactorily for detonation. Essentially it seats the round farther and that takes up some of the firing pin's energy.

I'd take the bolt out of the receiver and then clean around inside the tube real well with a 1" cotton wheel. A shotgun barrel swab works well too.

R,
Bullseye

You said you replaced the hammer. What hammer did you use?
Sometimes a VQ hammer causes misfires.

I did use replace the original hammer with the VQ hammer but I didn't see any difference in the number of miss fires.

Thanks

Ed

Put the original hammer back in to the pistol and test again. The VQ hammer is lighter with the hole cut-out and has caused misfires due to the reduced mass.

R,
Bullseye

Minor thing some people miss is cleaning the extractor slot , next to the chamber. A little crud down in that will keep the bolt slightly back. A toothpick works to clean it. I use an old Norelco shaver brush for that, and the other "works" of my Mark III.

ruger22 wrote:Minor thing some people miss is cleaning the extractor slot , next to the chamber. A little crud down in that will keep the bolt slightly back. A toothpick works to clean it. I use an old Norelco shaver brush for that, and the other "works" of my Mark III.

Easy to forget, and it doesn't take a lot to crud that cranny up.
Toothpick or soft dental-pick plus some canned air to blow it out might help. It is an awkward angle to get in there.

It couldn't hurt to run some CCI mini-mags through there, they're about the gold standard for .22lr ammo as far as I'm concerned. Federal 550 are the silver standard, of course ... cheap, plentiful, and reliable. Every time I try another bulk .22lr I end up disappointed, and now that I think of it, most times I try a non-CCI non-bulk ammo I feel the same way in the end.