I just started running a 625 JM in my club's monthly steel shoot. It may very well replace my CZ 75B in that capacity. I'm looking to do a few things to it, including chamfering the charge holes in the cylinder if I can find a gunsmith that still does that (see my post in the gunsmithing area), and lightening the trigger pull a bit. I replaced the mainspring with one from Wolff, but I couldn't get it to ignite a single primer. No, I'm not using Federal primers, but I thought at least SOME of them would go off. Next, I bought an extended firing pin to help with the ignition, but again NONE of the primers lit. So, I took out the Wolff mainspring, left in the extended firing pin and there is, without surprise, 100% reliable ignition. I'd like to find a mainspring that has a stiffness somewhere between the Wolff spring (which doesn't list a weight) and the stock spring (which I don't know the weight of either). I don't want to switch to Federal primers because I currently have about 8K Tula primers which normally work wonderfully. Anyone have a recommendation on a different mainspring or a way to make the Wolff spring work?

I've never tried this (all my Wolff RP mainsprings seem to work fine), but I have heard that you can take a spent primer, remove the anvil and place it over the end of your strain screw and then tighten it all the way. Good luck.

Adios,

Pizza Bob

PS: I was under the impression that Tula primers had some of the hardest cups - others may comment.

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NRA Benefactor Member

I may have to give that a try.
You may be correct about the Tula primers, but during the gun craziness that was going on, it was almost impossible to find primers. Powder Valley was able to stock Tula primers and I bought a bunch of them. Other than the issue I'm having with the 625 they've worked great.

Yes. The Wolff Reduced Power Mainsprings work fine but frequently require a longer strain screw with "hard" primers. A 3/8" long 8-32 socket set screw makes a great (adjustable) replacement strain screw. Use 222 loctite to keep it from loosening.

Great tip. Thanks.

I use the wolff springs on my JM 625. I also replaced the firing pin with an
extended one from cylinder and slide. Only shoot reloads with federal primers ( they seem the softest )
Their seems to be a difference in the thickness for different full moon clips.

Last week I tried the set screw idea and it worked beautifully. That, in combination with the Wolff mainspring and a 15 lb trigger rebound spring has made a considerable difference in the trigger and it's now reliable. I have so many Tula primers I will have to keep the mainspring a little more taut, but when they're gone I'll pick up some Federals and lighten it a bit more.

Bend the factory mainspring as required to give you the ignition force you need. I use a simple jig to make the job easier.

The jig is just 2 nails in a piece of scrap wood one inch apart. The jig isn't really required, it just allows you to put reference marks on the wood and control the process better for "a little more" and "a little less" adjustments.



A stock spring in the jig.



A spring bent to provide ~8 pound DA pull with a Wolff 14 pound rebound. Note the difference in the position of the base end. The witness mark drawn is how far the spring was flexed to provide the bend that gives this relaxed position.



A stock and bent spring side by side. A bent spring will provide a DA pull with less stacking than simply backing out the strain screw. It is also (IMO) a more robust installation than depending on thread locker to hold the strain screw and maintain spring tension. Others may argue against that statement. They are welcome to their opinions.

Yep, that works. The only difference between a std and reduced power Wolff mainspring is the amount of arch.

The "more arch" is required to keep the correct hammer strut/link geometry when you run less spring pre-load.

As to the "robustness" on a loctited set screw, I've found they stay put better than the "way too soft" factory stainless steel strain screws that also need loctite to keep them in place. The tip of the socket set screw also won't deform like the stock stainless strain screw does.

Hard primers do limit what you can do. There's a considerable body of knowledge on theses guns. A lot of it you'll find mentioned here: 625PC Hammer weight Adjusting

With the stock spring, I have found by experimenting that you can back the screw out only 1/4 turn before you have problems. So, you could shorten the screw the right amount for a quickie trigger job. I have used the spent primer trick on a number of revolvers and it worked. Not much difference between work and not work. Some people have been known to turn the screw out before a trade in at a shop. Keep that in mind when buying used.

The spring kits sometimes do not work the way they are intended. I had one kit that I tried in my N frames and it made them worse. Horrible action. Then I tried it in a friends M28 and it was perfect. He loved it. Fired all ammo OK.

re: trigger return spring

I was trying to slick up a 617 via a major suppliers spring kit.

While it greatly helped, the trigger return spring proved to be simply too weak to reliably insure the trigger return to proper location.

With practice, my owner-built Slick-em action jobs have improved considerably. It's not so hard to get it smooth but to get everything as crisp as the factory pro job, and the more practice with the ceramic rods & what not to do, is weaning me off the need to support my local gunsmith so much.

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Dum vivimus Vivamas

Hi all...
Old thread .. old problem
I just buy a new mainspring and a C&S firepin for try to solve it, becouse my 625 JM work fine with small primers (Fiocchi brand), but the mainspring screw is at the stroke end. With CCI Large primers don't work.
I'll update the thread when i test the new setting ;-)

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Skid