Wolf K frame reduced power spring

[Wired]

I sent it back. it was much too weak to even get one shot off. New model 66-3. Wolf said to install extended tension screw, but i am not going to start throwing parts at it, including an extended firing pin.
The stock spring is completely unacceptable.
So, anyone have suggestion for another spring? Apex, Wilson, any others out there?

[notsofast]

I think very few people if any will agree with me but I have tuned trigger pull by backing off the strain screw, specifically a 8x 627 Pro. I put purple lockite on the threads, no problems it worked very well, and the purple locktite is easy release

[series guy]

On the round butt guns you need a longer strain screw to use a power rib main spring. McMaster sells a setscrew with nyloc applied that works perfectly. I think a bag of 10 costs around $6.00. Before changing springs there is other work that should be done first like smoothing some internal parts along with the inside of the frame where the rebound slide moves. It also pays to replace the rebound spring at this time as the two springs work together and need to be sort of balanced for lack of a better word. The McMaster part number is 95235A507.

[Jim Sharp]

To the OP: in my experience a reduced power main spring, regardless of manufacturer, will work best with a full length (read OEM) strain screw. If your strain screw has been shortened at some point it may now be too short to work well with an after market spring. I also concur with series guy on the need to use a rebound spring that is "balanced" with the main spring, as well as polishing the rebound slide. Finally, apart from the metallic ping sound that the Wolfe Power Rib makes, it's as well made and effective as any from other manufacturers.

All in all I'd recommend the spring change be made by an experienced gunsmith. Good luck on what's one of my favorite revolvers. Enjoy!

[Gunhacker]

A classic issue with the Wolff reduced power mainspring with the "power rib" incorporated into it. It creates a recess that the strain screw now fits into, necessitating the need for a longer screw to properly tension the spring.

On round butt grip frames, the longer strain screw for a square butt grip frame does the trick. For a square butt grip frame, you have to go the route of making one from an 8-32 screw.

I've read that there are some that have used a spent primer cup (minus the anvil/internals) slipped over the end of the strain screw, which spans the width of the power rib recess, making a longer screw unnecessary.

I went the longer screw route on my round butt 625-8 and installed the square butt strain screw.

BTW... How did I discover that a square butt strain screw works for a round butt grip frame with a Wolff spring?

When I bought my 986 Pro, it was advertised as having a (reduced power) Performance Center mainspring. I wanted to satisfy my curiosity about what the PC mainspring looked like versus the normal stock spring, so I removed the grips.

Well... not only did the mainspring look exactly like a Wolff spring, power rib and all, but the strain screw installed by S&W was unmistakably a longer square butt strain screw.

So when I installed a Wolff reduced power mainspring in my 625-8, I copied what the factory did on my 986, and it worked correctly right out of the chute.

[Nick B]

I thought I read on here that a replacement screw from Ace Hardware can work as a strain screw . Anyone know what size and thread pitch to ask for ?

[Protocall_Design]

That would be #8-32 x 1/2" long set screw. The set screw is headless, so you can tension the spring to where you want it without a head to bottom out. If you want a screw with head, you can get a socket head cap screw the same size and work the length down to where the head seats at the right spring tension. You need to use #242 Blue LocTite with the setscrew. Once the LocTite sets up, it will still be easily adjustable, but stay where you turn it to with the wrench.

How do you know what the right tension is? You go to the range and fire your normal ammo. If you are getting misfires, tighten the strain screw about 1/8 of a turn, try again, more misfires, tighten again, and so on. When you are getting no more misfires, you're there. I like to give it another 1/8 turn after that for insurance to catch that 1 in 100 that might still misfire.

Then hook a trigger pull gage around the top of the hammer and see what the number is when the hook just lifts off the frame. Record that number for future reference. Now you can shorten the strain screw till you get the same hammer pull weight when the screw head bottoms out. Once that is done, use the lightest rebound spring that give you the trigger return feel that you want. Job done.

This sounds a bit complicated, but actually very easy to do and only takes a few minutes. This way you are not just blindly hoping someone else made a screw the right length. You are actually measuring it yourself and know it will work with your ammo.

[Wired]

THANK YOU All. Extended screw inbound
I appreciate the detailed responses

[Arquebus357]

When S&W converts a square butt frame into a round butt frame some metal is removed from the grip frame where the strain screw is located. To compensate they cut the screw head relief a bit deeper so they need a bit shorter screw.