Changing mainspring on MKII -- how much of a b-zitch?

[Roogalator]

I've been having intermittant failures to fire with my MKII lately, and since the rounds that fail to fire have visible (but apparently weak) primer strikes I'm thinking it's time to replace the mainspring.

My question is how much of a wrestling match is it to replace the mainspring? It appears as if all you have to do to remove the spring is drift out the pins that hold it in. However, I have visions of a real death struggle trying to reassemble with the new spring -- spring, ball, pins flying off into the stratosphere, Roog gnashing his teeth, tearing out his hair, etc etc etc.

Anyone ever done this before? How much aggro should I expect? Is there some special procedure one needs to follow to do it correctly?

[Roogalator]

C'mon here folks, am I really to assume none of you know anything about this??? SOMEbody's gotta have some info on changing out MKII mainsprings.

[zukiphile]

I've never disassembled one. How much is a new mainspring assembly?

If you try it, let us know how it went.;f

[Roogalator]

Brownell's has the mainspring itself for a buck seventy-four. I've no intention of replacing the entire assembly ($22.59 chez Brownell) unless absolutely necessary.

[zukiphile]

Originally posted by Roogalator
Brownell's has the mainspring itself for a buck seventy-four. I've no intention of replacing the entire assembly ($22.59 chez Brownell) unless absolutely necessary.

I feel your pain, Roo. At least you know you can get another if you botch the job.

[MatGlock]

A few years ago, I tried to replace mine. Some ball bearing shot out and I had to order a whole new assembly. I consider myself to be fairly mechanically inclined, but if I were you, I would order a whole new assembly.

[Roogalator]

Gaaaahhh. That's exactly what I did NOT want to hear. Oh well, I'm gonna give it a try anyway and see if I can make it happen. What have I to lose but my sanity and a few dollars...?

[zukiphile]

Originally posted by Roogalator I'm thinking it's time to replace the mainspring.

An intermittent weak strike might be something else.

What if something else is to blame?

Are the firing pin and the channel in which it rides clean? Does the inside of the frame look like sand was dumped in it? Mine does, and it makes things a little gritty. Does the hammer swing freely?

Looks as if you've focused on the hardest part to fix. I would start with easier possibilities.

[Blitzer]

Originally posted by Roogalator
Gaaaahhh. That's exactly what I did NOT want to hear. Oh well, I'm gonna give it a try anyway and see if I can make it happen. What have I to lose but my sanity and a few dollars...?


Ditto on something else. Take to bolt and dunk it in solvent and brush it with an old tooth brush. Shake it out and blow it out with compressed air.

If that fails put the assembly in a large 2 gallon ziplock bag and disassemble it in the bag. It will retain the parts if you oops them!

[Roogalator]

Actually I'm meticulous to the point of obsessiveness about cleaning the working parts of my guns. With the MKII I always clean out the firing pin channel. I also clean and lube the bolt and hammer pin. I'm fairly certain I've eliminated various mechanical failures as causes of the problem, and at this point I'm ready to implicate the mainspring despite the potential industrial strength headache of replacing it.

I note with dissatisfaction that neither Brownell's nor Wolff (nor Ruger for that matter) offer increased-power mainsprings for the MKII, though Wolff (for reasons passing understanding) offers reduced-power mainsprings. So I will have to settle for a standard weight spring and hope that does the trick. Harumph.

[MatGlock]

I have shot a lot of rounds through my Mark II, probably close to 80,000. I replaced the mainspring at around 50K, and I must say reliability did improve, dispite my frustration.

[zukiphile]

Originally posted by MatGlock
I have shot a lot of rounds through my Mark II, probably close to 80,000. I replaced the mainspring at around 50K, and I must say reliability did improve, dispite my frustration.

Was that frustration worth saving $20, or do you wish you had just ordered the whole assembly?

Roog, you asked why Wolff's used to carry a reduced power mainspring. Guys use those for a lighter trigger pull.

[MatGlock]

I didn't save a dime. I had to order the whole assembly. I could not get it back together otherwise. If I had just started out ordering the assembly I would have saved a few bucks for the spring and shipping. I think I ordered direct from Ruger. Mark II's are great pistols, but no one ever intended them to be taken apart. (they shoot better dirty- clean sparingly.)

[zukiphile]

Originally posted by MatGlock Mark II's are great pistols, but no one ever intended them to be taken apart. (they shoot better dirty- clean sparingly.) [/B]

Then mine should be tackdrivers.

MG, thanks for relating your experience on this. If it's any consolation, you saved this mechanically challenged shooter some future time, money and angst.

[Hound Dog]

I bought a 'spring pack' from Midway.com a couple months ago for my MkII; manufactured by Wolff Springs. It had 4 springs - a reduced power trigger & firing pin spring, and a standard mainspring and 'guide-rod spring' (or whatever it's called - the one that fits in the upper part of the bolt carrier thing (excuse the terminology - I am not a gunsmith)). Anyway, the only spring I couldn't replace myself was the last one, as that spring assembly is crimped into place or somehow attached so that I could not remove it.

The mainspring was a pain in the bootocks to replace, but I did it myself without any real problems. First thing to do is make sure you are somewhere that makes it easy to find small parts on the floor (out on the back yard or on shag carpets is a very bad place). Second thing to do is to remove the pin at the bottom of the assembly. Point the assembly at the table top so that you can catch the components as they fly out of the housing. That spring is STRONG and there is a small metal ball at the end that just want to go sailing off into the distance given the chance. Also, my pin was in there really tight - I had to use a nail with a hammer to punch it out. Once the pin is out, the pivoting piece will get pushed out of the way by the spring. Simply remove the spring and insert the new one (after searching the floor for the pieces that went flying out once the pivot piece was out of the way. There should be the housing, the pin, the pivot piece, the spring, and the metal ball.

Now comes the fun part - you need (idealy) at least 3 hands made of steel to do this easily. You must set the ball on top of the spring and compress the spring with the pivoting piece on top of it, and press it down far enough to line up the holes for the pin. Sounds easy in concept but is difficult in execution. I believe my final solution (after flinging the metal ball all across my living room a couple times) was to get a piece of wood with a small 'dent' in it near the edge of the wood. I set the ball in the dent (so it wouldn't roll away), and put the spring (in the housing) upside down on top of the ball. Then, I compressed the spring by pressing the housing downward. THEN, I had to slip the pivot piece in on top of the ball, while making sure I didn't move it too much and send the ball flinging across the living room. I eventually got the pivot piece in place and pinned it. Took me about an hour but it was done without any expense or gunsmithing training. It's tedious but doable.

I did this to correct a jamming problem I've been having (about 2 out of every mag stove-piped and I couldn't isolate the cause of the problem, so I replaced the springs to troubleshoot. Never hurts having new springs, anyway. After all this, it still jammed. I took it to my range finally, and after a couple minutes the gunsmith there announced that he had found my problem. The extractor was missing. As in, broke off. Still, it functioned 80% of the time without an extractor. I absolutely LOVE the MkII. I just wish they could make one in a larger calibre.