Question regarding strain screw length

[bountyhunter]

bountyhunter, how about some info on main spring bending??

thanks,

Stu

I do a mandrel bend over a screwdriver handle with my panavise to make sure it's a progressive curve. I center the point of bend about 1/3 of the way up from the base (widest part) of the spring. Sometimes I lay the spring on a piece of paper and trace the curve so I can check after bending. To reduce spring force you just increase the curve. To get stronger spring, you flatten it.

 

[andyo5]

Also, thanks Andy!, the workaround with the shim is also good information for people who don't reload any may not have ready access to a used primer.

You're welcome. But I don't think of the shim as a workaround.
A primer cup is...how thick? Do you have a selection of primer cups of varied thicknesses, so you can get the right resistance? Seems to me that the primer cup is what you do if you can't make a shim.

 

[stu1ritter]

SeamasterSig, two weeks ago I received an order from S&W with 10 square butt and 4 round butt strain screws. They still have them.

Stu

 

[jimmyj]

I have a pre-model 15 4" Blued that had issues.
I called S&W Customer Service and ordered a new mainspring and screw.
On arrival I compared the replacements to new modern ones and found there is a very slight differences in length between the replacements and the on hand new ones.
I had been advised that there were the same no matter what the vintage, but there is enough to make a slight differences.
The ones for my older revolver had a different stock number than the more modern ones per S&W rep.

 

[SeamasterSig]

You're welcome. But I don't think of the shim as a workaround.
A primer cup is...how thick? Do you have a selection of primer cups of varied thicknesses, so you can get the right resistance? Seems to me that the primer cup is what you do if you can't make a shim.

To me they are both workaround solutions, i.e. as opposed to replacement with the original part. But I understand what you mean. A selection of shims would certainly allow for more precise control of the overall screw length. In this case, the first primer I grabbed brought the length to within a few thousandths of the size indicated above in post #7, so I should be good to go for the time being. The trigger is back to "heavy but smooth".

SeamasterSig, two weeks ago I received an order from S&W with 10 square butt and 4 round butt strain screws. They still have them.

That's strange, I just got off the phone with S&W and the service rep I spoke to looked it up and swore the "old school" square butt screw was out of production. Do you have a part number that would work with an early mid-80s model 66?

 

[federali]

Check First

Before doing any strain screw work, you should first check the double action trigger pull using a scale or weights. If the trigger pull is within factory specs of about 12 pounds, the screw should be left alone. If heavier than spec, you may take it down a bit, constantly checking trigger pull.

Some people think that screw is for action adjustment. Once loose, it unravels on its own and eventually the gun no longer fires. An SD handgun should always be tuned for reliability over accuracy.

 

[stu1ritter]

SeamasterSig, the screws I ordered were blued with 05035B000 for the RB and 05064B000 for the SB since almost all of my guns are blued. What is an "old school" strain screw anyway???

Stu

 

[SeamasterSig]

Thanks, Stu! I called up S&W again today and gave them the part no. for the SB screw and the rep said they have plenty in stock and offered to send me a couple free of charge. Not a bad deal!

 

[Nick B]

Since we're talking strain screw length when an un-altered screw is fully tightened should the screw head be flush with the back strap of the grip .
I have a model 10 where the screw head sticks out some even though it's fully tightened . It came that way when the gun was bought new back in the 80's . Doesn't look very good .

 

[andyo5]

Since we're talking strain screw length when an un-altered screw is fully tightened should the screw head be flush with the back strap of the grip .
I have a model 10 where the screw head sticks out some even though it's fully tightened . It came that way when the gun was bought new back in the 80's . Doesn't look very good .

I believe that the older version of these screws protruded like you said, The wooden grips were relieved, if necessary, to clear the screw head. Later versions shortened the screw head so it would be flush with the grip frame.

 

[jculloden]

S&W is sending one for my 13-2 NO CHARGE !!!

 

[andyo5]

The problem is that once you install the new factory strain screw, you will find out why the previous owner had shortened the original one.

 

[SeamasterSig]

The problem is that once you install the new factory strain screw, you will find out why the previous owner had shortened the original one.

The strain screws I recently received from S&W measure 0.6045 inch, which makes the trigger a wee bit stiff But it's still very smooth, so I can live with it.

 

[jimmyj]

Jimmy's solution:

Call Smith and Wesson Customer Service at 1-800-331-0852.
Give the Rep the model number and serial number and request a mainspring spring and strain screw. Despite popular belief there is a minor differences in the lengths between older and newer models.

 

[trea]

Was having light strikes with my 66-2. Strain screw look like it was never touched but I ordered a new one anyway. It was 8 thousand longer than the one in the gun. I didn't think it was enough to make a difference. But it was no more light strikes.