strain screw vs. Wolf main spring?

duckloads · Oct 19, 2010

a while back, I replaced the mainspring on my 625-9 (45 Colt) along with the rebound slide spring. I shot 2-300 rounds without a problem. I also dry-fired the gun "many" times.

Now, I get 2 FTF's out of every cylinder. The strain screw appears to have formed itself to the rib contour of the Wolf main spring, effectively making itself shorter.

What is the fix?

Thanks

srgvaz · Oct 19, 2010

duckloads said:
What is the fix?

Replace it with a new one.

duckloads · Oct 19, 2010

srgvaz said:
Replace it with a new one.

Replace it with a new one every 2-300 rounds?

bountyhunter · Oct 19, 2010

duckloads said:
Now, I get 2 FTF's out of every cylinder. The strain screw appears to have formed itself to the rib contour of the Wolf main spring, effectively making itself shorter.

What is the fix?

Thanks

Don't use wolf ribbed springs. That's why I quit using them. I just bend the stock springs now.

You have to either get a new strain screw (which are pricey) or put a shim under the one you have which is a royal pain since it will fall out when you take it down to clean it.

I always warn people about this but most people don't pay attention. Wolf needs to coin a flat spot on the spring to engage the tip of the screw. It's a bad design as is.

duckloads · Oct 19, 2010

bountyhunter said:
Don't use wolf ribbed springs. That's why I quit using them. I just bend the stock springs now.

You have to either get a new strain screw (which are pricey) or put a shim under the one you have which is a royal pain since it will fall out when you take it down to clean it.

I always warn people about this but most people don't pay attention. Wolf needs to coin a flat spot on the spring to engage the tip of the screw. It's a bad design as is.

Thanks Bounty' Now I believe.

tomcatt51 · Oct 19, 2010

Actually, the problem is the heat treat/alloy S&W uses for the stainless steel strain screws. It's ridiculous soft and mushrooms/deforms even against the stock spring. The carbon steel strain screws from the blued guns are a better choice as a replacement if you feel compelled to use a stock strain screw.

OKFC05 · Oct 19, 2010

A Grade 8, 8-32 cap screw can be ground to length and shape on the end, and is hard enough to hold the strutted mainspring shape a long time. I have some in service over 10 years.
Available at hardware stores.

HEADKNOCKER · Oct 19, 2010

That has been my fix for use with the Wolff Mainspring a 8-32 Stainless Allen screw with blue locktite tape on it..
Adjust till the light strikes go away & then 1/4 turn more..
I keep a small packet of these screws in my goodie bag now..

I have also had good luck bending the factory spring as well..

dkp9782 · Oct 19, 2010

Just take a USED primer, pull out the anvil, and slip it over the screw where it contacts the mainspring!

Chuck Jones · Oct 19, 2010

one of my used guns had piece of a worn-out thin swiss file blade as a shim. needless to say it didn't move around. I thought it was pretty clever.

/c

bountyhunter · Oct 19, 2010

dkp9782 said:
Just take a USED primer, pull out the anvil, and slip it over the screw where it contacts the mainspring!

I don't reload so I hacked the bottom end off some spent .22 cases and used them as shims. Pain in the rear.

bountyhunter · Oct 19, 2010

OKFC05 said:
A Grade 8, 8-32 cap screw can be ground to length and shape on the end, and is hard enough to hold the strutted mainspring shape a long time. I have some in service over 10 years.
Available at hardware stores.

I toyed with the idea of tip hardening some strain screws using a flame and kasenit but was too lazy to do it. We use that stuff to surface harden hammers and sears. It would probably work on screws.

duckloads · Oct 19, 2010

Thanks again for the conversation. I replaced the stock spring until I can buy some 8-32 socket head screws.

tomcatt51 · Oct 19, 2010

duckloads said:
Thanks again for the conversation. I replaced the stock spring until I can buy some 8-32 socket head screws.

Use a socket set screw put a notch in the socket end so you have a reference for re-installing it if you disassemble the gun. 290 wicking Loctite works real well. Just put a drop on after you've done your adjusting.

bountyhunter said:
I toyed with the idea of tip hardening some strain screws using a flame and kasenit but was too lazy to do it. We use that stuff to surface harden hammers and sears. It would probably work on screws.

Doesn't harden stainless.

SPDGG · Oct 20, 2010

dkp9782 said:
Just take a USED primer, pull out the anvil, and slip it over the screw where it contacts the mainspring!

+1 Agree, Works every time

srgvaz · Oct 20, 2010

duckloads said:
Replace it with a new one every 2-300 rounds?

If the spring mushroomed the screw replace the screw and replace the stock spring. Unless you want to repeat every 2-300

... As stated you could use a carbon steel screw and that may fix the issue, or you can bend the stock spring. I prefer stock with no bends on my guns I wouldn't compromise reliability over comfort.

MR.G · Oct 22, 2010

I ordered a couple of new screws from the factory and they didn't cost much. They came with a mushroomed end, not like the original which was flat when new. They are also slightly longer than the original screws, which works well with the ribbed spring.

srgvaz · Oct 22, 2010

Be great if you can upload a pic of what they look like.

imashooter2 · Oct 23, 2010

dkp9782 said:
Just take a USED primer, pull out the anvil, and slip it over the screw where it contacts the mainspring!

I did this on installation of the spring when I noted that the stock screw would be in the rib channel. Many thousands fired since. No issues.

duckloads · Oct 23, 2010

I bought several 8-32 s/s socket head cap screws. I also bought some carbon steel screws, but I do NOT like the idea of the screw being harder than the spring. At this point, I do not want to wear the spring.

I ground the head down to the same diameter as the stock screw, so it would fit in the recess / counter bore in the frame like the stock screw.

I started with a 3/8" long screw with the above head treatment, but still got misfires. I then cut a 1/2" long screw down to 0.030" (or about 1 turn) longer than the 3/8 screw. I have yet to test fire that one, but it feels somewhat stiffer.

On both of MY screws, I beveld the end of the screw, so that it would fit INTO the spring's rib. If I get the length right, I do not want it to wear down into the rib like the factory screw.

strain screw vs. Wolf main spring?

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