MK1 constant misfire caused by old hammer spring?

[peter_reinhard]

I shoot in the standard 22 Gallery Match between 6 gun clubs and my MK1 recently started to misfire. Of course I can't have many alibis and you are allowed only one DNF per year (which I have already used). So I'm trying to figure out what is wrong. I'll borrow someone's spare gun until I figure this out.

About every 5th shot, you just get a click, but no discharge. When you eject the cartridge, it has been hit on the rim, but it looks a little light. Thought it might be a bad batch of ammo, but other ammo fails as well.

During the past year I've replace many of the parts including firing pin and it's spring. Did a trigger job including pollishing the hammer and sear. The trigger release is very good and the gun is accurate with a TruGlow sight. Also Volquartsen grips (Mark 2 fits the A100 frame).

Since the gun was made in the early '70s, do you think it could be the hammer spring is a bit weak? and if so, has anyone had any experience changing one out? I can do most things with the gun except this. I'm sure I can get the spring out, but may put my eye out, and can't imagine how I'll ever get it back together with that ball bearing in place. Maybe I'll send it to Ruger.

The spring kit I bought includes a hammer spring, but was told not to change the hammer spring (make it lighter) because I might get mis-hits (like I'm getting now). So if I do change it, maybe I'll get an OEM spring from Ruger instead of using the volquartsen spring.

Anyway, any ideas would be appreciated. I'm trying to compete with guys with Pardinis, Benellis and Smith 41s just to show the old $200 Ruger can do it.
Thanks

 

[Tommy Kelly]

Just a thought but try cleaning the extractor notch in the barrel. If it has a residue buildup inside it it will hold the bolt back just enough for the hammer not to hit the firing pin but not enough to stop the hammer from falling. it's a possibility.

 

[nvbirdman]

Do you have a friend who has a Ruger 22 auto? Try his mainspring housing (yes, the whole unit) in your gun to see if that solves the problem.
If you feel the need to replace the mainspring, send the whole mainspring housing to Ruger. They know how to do it without making parts fly and it would probably be a quick and cheap turnaround.

 

[contender]

Two excellent ideas above.

 

[peter_reinhard]

Thanks guys. I don't recall the extractor hole to look dirty, but I've never giving it much attention.
A few guys have Mark IIs as spares and I'll see about borrowing the entire mainspring assembly before replacing anything.
Both great tips and I'll post a follow-up when the problem is cured.
Thanks again.

 

[rugerguy]

yes, cleaning is a common 'culprit'....check the chamber as well the face of the bolt (rim pocket), and make sure your firing pin "protrusion" is correct. Make sure the hammer is NOT rubbing on the insides of the bolt, causes drag and misfires too!! lots of things to look at, and for, ANY 22 rimfire firearm..........and yes, of course the ammo!!
never use any ammo in competition , that you may have dropped as the "fulminate" (primer) inside the case can crack, break loose, cause misfires....years ago this was quite common with Remington 6100 ammo and being they were in "plastic case" and the delivery man may "drop it too hard" this happened ,saw this with CCI too...turn the cartridge 180 degrees and it would fire?? go figure, but never say never..............