I just finished rebuilding my grandfather's model 510 farm gun, so I'm a little familiar with them. There's lots of good advice here already, here are my thoughts:



I don't know how old the rancher is, but he does remember that the safety re-sets every time the action is cycled?



Also, old ranchers often have old ammo. Most of them think it never goes bad.



If you are getting good primer indentation, its probably not the firing pin spring. How heavy is the trigger pull? I lightened the trigger pull considerably by surface grinding the face of the "plunger" that goes thru the firing pin spring and still get 100% ignition. Shortening the plunger face has the same effect as shortening the spring itself, but is easier to do neatly (and a little bit goes a long way). If it is a firing pin spring power issue, the trigger pull would probably be very light (around 5 lbs is normal)and it could be that the spring itself is fine, but the plunger face is overly worn.



How is the headspace? Does the bolt close hard or easy on a loaded chamber (with no firing pin or spring). Too much headspace, combined with thinner rimmed ammo might be a problem. I added a .0075" bolt shim from a model 513T to tighten mine up. This also increased the trigger pull by causing the firing pin spring to compress more.



These are unusually reliable guns with very powerful firing pin springs. My best guess is there is either roughness/pitting/crap binding the spring, plunger or firing pin, or its operator headspace. Since you haven't been able to replicate the problem yourself, its probably a worn brain-housing group. If possible, have him bring his ammo and shoot it with you watching. - John

To all,

Had a rancher bring in a Rem M512-x bolt action 22 LR that was miss firing. He said it only does it when he leaves it loaded for extended periods of time with him in his ranch truck.

He stated that there was a time that the gun was stored for several years cocked. I replaced the firing pin spring and tested teh rifle with fresh ammo and it fired 50 rounds without a hick-up at all.

Sent the rifle home and two days later the rancher showed up again. He said he tried to fire the rifle for the first time since he picked it up. He had loaded it when he took it home and it set over two days and then missfired with fresh ammo I sent home with him.

I have tried to make the misfire occur by leaving it loaded(on safe) for a few nights in the gun safe but everytime I do that it fires perfectly with very good indention on the case rim.

I am beginning to wonder if the bouncing around in the truck is causing something in the feedign system to move and retard the movement of the firing pin.

THere is one rub mark on the bottom of the pin so that will be my first place to start but other then that I am a little baffled by this little rifle.

If I could reproduce the misfire I would feel better as I would at least know what happened to the rifle until it was fired.

I tried to tell teh guy that if he just kept the mag tube full of ammo and load it when needed, it would not only be much safer but also fire with 100% reliability. He wanted nothing of that and obviously something is not quite right.

Any ideas would be great if any of you have seen this type of problem with the 512 or other 22 LR rifles.

Thanks for the information, will let you know if I find the problem.

Good Shooting!!!

50

Howdy,

Fifty, try a new firing pin. It seems that under spring tension, that spring can jiggle somewhat and gouge the pin. An alternative might be to really polish the pin well, re-lube it with something with moly in it, and try again. I worked on an older Rem. rimfire that did the same thing. It stopped with a new pin.

Coach

Hit the guy in the head with a hammer . Maybe he will get some sense and not keep it loaded and cocked as he bounces around in his truck .

Dahh...Kinda like tellin someone to not drive around with their truck doors open to keep the doors from getting dented when he hits stuff with them....

Coach Hunt,

Thanks for the response, the rancher does not want to spend much for the repairs, ever hear that before?

I replaced the spring again with a heavier one still and noticed there was a little bit of a click when I ran the pin through the bolt body, tomorrow I will polish up what ever is catching and lube the pin up to see how it works.

Its pretty difficult to figure out what is wrong when I can not reproduce the problem, it is obviously something contacting the pin when it is released.

Thanks for the input!

Good Shooting!!!

50

GSP7,

I fully agree with your comments. I did voice my concern for carrying the rifle loaded but it when in one ear and out the other.

Still I would like to solve the problem and not just the symptoms.

Thanks for the reply!

Good Shooting!!!

50

Several years ago I remember a report in one of the gun rags about how the primer material in a rimfire like the .22 LR can be jarred out due to extended vibration. The example was a .22 carried in a pickup truck that bounced around on ranch roads all the time.

Now that may not be the case here, but if you failed to reproduce the effect and he had problems, I'd look to seeing if he had the problem with fresh ammo that wasn't carried in the rifle all the time.

Just a thought!

Maybe heat from being in the truck is closing the tolerances between the pin race and the pin; or distorting one or the other, or both?



I'd dry-fire with the action pulled and see if trigger pull technique (squeezing vs. slapping) could be causing a rub or drag on the firing pin.

When he said it wouldn't fire, did he bring the round with it that failed? Did it show the firing pin indentation? I wonder if the primer could be the problem. Gotta be honest though, morons like that don't really deserve a working gun, better for him to have to clear it and chamber a fresh round. :-)

Red

Is there any chance the rancher is loading the first round by dropping it into the chamber, instead of loading from the magazine with the bolt? If so, it's possible that the extractor is keeping the bolt from fully travelling forward, preventing the firing pin from making good contact with the rim.

I'd ask him to load it in front of you.

Good luck.

I would take the pin to a buffing wheel, maybe even give it a couple licks with some sandpaper first. Give it back to him with the instruction that if it misfires to bring the shell in with the gun. If it is very dusty/gritty and the gun is upside down it may settle in the action that way, so if he does store it upside down have him try keeping it upright, or in a case.

Fiftydriver, when it misfire occurs is the cartridge rim indented? If not could the pin be getting out of alignment with the so it hangs up when released?

I have a friend that carries a 77/22... while i am sur ethis aint the problem, his rifle is KNOWN for being full of dirt... it has actually been "cleaned" at a carwash, to clear the grease and dirt.

I'ld ask the fella to bring in the rifle, with a couple failed rounds. Perhaps asking him to drive around for 3 days, attempt to pop, bring you that case.. repeat 2 or 3 times, and then, bring you the rifle (shesh;; loaded.. damn) or you can visit him, and try the rifle...

what make is the rifle?

and of course he want's a 200$ repair, for 5 bucks

jeffe

"Hit the guy in the head with a hammer"
Then change the pin.

I don't any one mention ammo have you tryed some of the ranchers ammo. Maybe he had that around to long or it is bad ammo.I brought some cheap Aquilla once I had over 50% misfired on it.

To all,

Thank you for the replies, There is alot of ideas to check out.

I to was at first curious about the age and quality of the ammunition so after I replaced the spring and returned the rifle to him, I sent him home with a box of fresh, known good quality ammo.

He loaded the rifle rifle in front of me and loaded it from the mag tube.

I am beginning to wonder if while bouncing around in the truck(still blows my mind that he would want a loaded rifle sitting next to him bouncing down a rough farm road!!) the firing pin is rotating slightly and when fired, it is binding in the bolt.

He did bring me the last round that misfired, one of the fresh rounds I gave him and there was not even a hint of a strike from the pin so obviously the pin is binding somethere in teh bolt body.

Will head over to the shop here in a little bit to see what I can find out.

I though about loading the thing and driving up and down the gravel road but then though, I do not need to be as reckless as the owner, my luck, it would not miss fire and give me a 22 caliber sun roof, no thanks!!

Thanks again, any other ideas please feel free to let me know. I will up data you once I figure this little problem out.

Good Shooting!!

50

The firing pin should not be able to rotate because its "nose" is offset from its body and both are captured by the interior surfaces of the bolt.

If anything is shifting, it would be that round, U-shaped part that one of the bolt cross-pins goes thru. This part transfers energy from the firing pin spring plunger to the firing pin. Maybe it is binding on the cross-pin.

Still, here's my analysis:

-You can not replicate the problem
-You watched him load it properly
-There was no indentation at all on the new ammo

I bet he's not taking it off safe before pulling the trigger.

Beelzebubba,

I checked the safety to see if it was working correctly and it is. Then the rifle is loaded and on safe, the trigger can be pulled and nothing happens.

THe owner of this rifle says the firing pin falls when he pulls the trigger and it sounds like a dry fire.

Been playing around with this little 22 all weekend in between other jobs. Here is what I have found so far.

1) I can leave the rifle loaded and on safe and stored in the safe for three days and everytime the rifle will fire properly when tried tht first time.

2) The owner carries the rifel with him all the time in his truck so that leads me to believe that since it can be stored in a still postition and still function after three days, something is being vibrated and moved from the ride in the truck.

3) With the bolt disassembled, I found that the pin can in fact rotate roughly 10 degrees in both directions from wear on the actual firing pin. When I push the pin to the extreme in both rotational direction, and slide the pin forward, it catches on a lip in the firing pin passage hole in the bolt.

Here is my opinion on what is causing this problem. With the rifle cocked and in the rough riding farm truck, the firing pin is shifting one way or the other. Over a day or two of this, the firing pin, when released is binding into the bolt and stopping the forward motion of the bolt.

When the rifel is recocked, the pressure is released from the bolt and it realigns correctly in the bolt. When fired again, the bolt is in the correct location and hits the rim properly.

My suggestion to the owner is that a new properly fitted firing pin may solve the problem but there have not been any around for several years.

One could of course be made but for the labor involved, he could get a new 22 rifle.

To eliminate the problem, I will suggest that he keeps the magazine tube loaded, but keep the chamber empty and when he needs a shot, just load a round from the mag tube like he should be doing.

Like I said earlier, I have close to 100 rounds through this rifle jsut shooting it in a normal fashion and it has never failed to operate properly.

I guess the good news is that this is one way to keep the rifle safe and unloaded while bouncing around the farm roads with this rancher.

We will just have to see how he feels about my recommendation!

Thanks for all your information, all of you are always a huge source of information.

Good Shooting!!!

50

Fiftydriver,

Sounds like you have solved a tough one. I get 5 to 10 degrees rotation in my pin, but no hang-ups. They may be made that way to keep crud from locking them up. I've heard CMP is or was recently selling (used) complete 513T bolts for $5.00, but I think your solution is best. He must have some seriously washboard roads! Thanks for the follow-up - John