A couple of months ago I received a Mosin-Nagant .22lr single-shot trainer.  I've never owned a .22 before and this thing won't set off the catridges.  I disassembled and reassembled the bolt and gave it a good cleaning, and everything looked ok to me (firing pin etc.), but I think the firing pin spring just isn't as strong as it used to be.  The gun is stamped 1956 on the receiver and is all original.  The only ammo I have is some cheapass Thunderbolts I got at the local hardware store (gotta love rural Missouri!), but a friend of mine tried some different ammo (I'm unclear on manufacturer, but it wasn't a name brand that I recognize like CCI, Federal, or Remington, it was some crap he had lying around) with identical results.  Maybe 1 in 5 shells will fire.  Shells that do not fire will not fire on a restrike, you can strike them over and over but they won't go off.

I cannot find a replacement firing pin spring anywhere.  Numrich doesn't have one, Wolf Springs doesn't make one, and nobody has spare parts for this old C&R rifle lying around.  I'm thinking the only solution is to find some ammo with a soft enough primer that even this weakened firing pin spring will set the cartridge off.

Suggestions?

You should try to buy any different type/batch of ammo before getting frustrated. If you extract a round and see a good pin strike, one that nails the rim flat at the strike, another ammo selection is in order.
If it has a minor strike, a smith can answer what it needs.
 Rimfire ammo is a cruel world sometimes. Try another batch first, any other will do.

Duke give my cousin a call.
Lee's Gun Parts
972-790-0773
He's open 9-5 tuesday wednesday and thursday.

If he don't have one, or know who does,  it don't exist.

Stand by for image spam:

I took out the digicam and took pics of the firing pin/bolt face and some of the casings that I saved for analysis, one fired and the rest unfired.  The unfired casing that is in the middle of the other two unfired casings was restruck about 5 times and it never went off.  The face of the firing pin seems mangled to me, you can see that it is bending the rim of the casing when I restrike but I don't really see a sharp hit anywhere like you would from a Ruger 10/22 firing pin.  I'm used to centerfire firing pins so I don't really know what to look for here.

What do you guys see?  P.S. my new digicam owns.

Definitely light strikes.  And it does look like the firing pin is the probable culprit, tho its kind of hard to make out.

Prior users probably dry fired the thing to many times.

A gunsmith should be able touch the pin up with a little welding then repoint it.

I cleaned up the firing pin myself today with a file.  The firing pin spring, on the other hand, is pretty much a lost cause.  Bano I called Lee, he was a pretty cool guy but didn't have a spring and didn't know where I could get one.  He said check Sarco and start hitting hardware stores.  We chatted for awhile.

That sucks that he didnt have one.
I got to thinking tho.
I think AIM was selling them a while back.
You might call and ask if they have any parts guns left, and possibly have a spring for ya.

All the stuff they get, I'm sure they have some that are nonfunctional and unable to sell, or ones that cobbled parts off of.

Duke-Nukem:

When you disasembled your bolt, by chance did you get the firing pin to actually come out? Did you have any problems trying to get it out, or did it just fall right out after the bolt was cleaned?

Sgtbutler

Check the headspace - if it is a little large, the firing pin can't contact the rim with full force.  Also look for peening of the chamber from dry firing the rifle.

The good news is that you could get someone to set the barrel back so slightly to correct the headspace.  The bad news is that it is a $40 gun, not worth the trouble; you might as well get a different rifle of the same type and keep this one for spare parts.

WECSOG idea for improving the headspace - squeegee some filled epoxy into the rim recess, then carefully ream the chamber leaving a thin film of epoxy for the case rim to rest on.  Cheap, and dirty.

Look at the rims on the rounds that fired - if they look "fat", that is a good sign that the headspace is excessive.

I think this gun is a good mule for practicing gun smithing on - you can drill holes in the receiver for scope mounts, bed the receiver, checker the stock, play with stains and finishes, and ....

drill out the existing bore, install a liner, and rechamber the barrel for a good grasshopper level gunsmithing task.  Then crown the relined barrel.

Think of all the fun you are going to get out of this little Socialist machine.