640-1 spring replacement

[dunflyin]

My beloved 640-1 has rather suddenly begun experiencing light strikes with a variety of .38+P ammo and in different charge holes. When I purchased it my Gunsmith and friend, the late Karl Sokol, an S&W Armorer, performed his "action tune" on the gun and it ran fine for quite some time. Am I correct in assuming this is PROBABLY a case of needing heavier springs? If so, I know Karl was always a proponent of Wolff springs. Any recommendations here? I'll probably tackle this myself-not that it's brain surgery- we just don't have a decent Gunsmith anywhere in VT that I know of any longer. Thanks in advance.

 

[Muley Gil]

Start by going to a factory mainspring.

 

[stansdds]

Could be the main spring is worn and is in need of replacement. I'm not a fan of lighter weight springs in firearms that are used for serious purposes.

 

[dunflyin]

No,Karl was loathe to lighten the pull also-if for no other reason than liability.

 

[dunflyin]

640-1 Soft strikes/spring changeover

Thanks for all your suggestions. I have not gotten around to doing this spring changeover but I have received two Wolff spring kits with which to make the changeover. One further question if you do not mind. I have received varying opinions on which spring to change first in an effort to remedy the soft strikes. Any suggestions here? Once again,thanks in advance.

 

[stansdds]

Light primer strikes = weak main spring.

 

[ken158]

Thanks for all your suggestions. I have not gotten around to doing this spring changeover but I have received two Wolff spring kits with which to make the changeover. One further question if you do not mind. I have received varying opinions on which spring to change first in an effort to remedy the soft strikes. Any suggestions here? Once again,thanks in advance.

Apparently you do not want a factory spring so the only way to see if a new Wolff will set off a primer - is to set off some primers. Keep in mind some primers are thicker than others which means some will need a harder hit to ignite. Be sure to test with your PP ammo.

 

[Protocall_Design]

Ammo is a key consideration with a lightened action. Federal primers or ammo with them is the easiest to ignite. Winchester is the next easiest, then Remington, with CCI being the hardest. If you want your gun to fire anything on the market, you will need a very heavy hammer fall. There is a huge difference between Federal and CCI.

 

[toad67]

Did your strain screw back out a bit?

 

[KAC]

Did your strain screw back out a bit?

No strain screw on a 640-1. Coil mainspring.

 

[stansdds]

Did your strain screw back out a bit?

J-frame S&W's use a coil spring, not a leaf spring and tension screw.