66-1 Light primer strikes?????

[Nomad Farrier]

Traded for an aesthetically sound 66-1 and finally got to shoot it today. To my dismay it light strikes about 30% of the time with hot 357 and light junk 38 special and everything in between. Im a real revolver fan but unfortunately Im not really educated on troubleshooting. Can anyone help or give suggestions?
Thank you

 

[BC38]

First thing I'd check is the hammer spring strain screw. It is located on the front strap of the grip frame about 1/2" from the bottom of the grip. Make sure it is screwed all the way in.
If that checks out the next thing to look at is the hammer spring itself - it may have been replaced with a weaker than stock spring in an effort to make the trigger pull lighter.

 

[ken158]

+1 on what BC38 said - the mainspring is designed to be tight to the frame as it was not designed to be a trigger pull adjustment.

 

[stansdds]

Welcome to the S&W Forums. Yes, first thing to look at is the strain screw, which is found on the front of the grip frame. Many people think this is a trigger pull adjustment screw, but they are mistaken. The screw is to be fully tightened and routinely checked as it can back out. If the screw is backed out, the trigger pull will be lighter, but the main spring will no longer have enough tension to impart enough power to the hammer to ignite primers.

 

[Alk8944]

About 99% of failure to fire are due to a loose strain screw as noted above. There is another possibility, and that is the mainspring was replaced with a Wolff "Power Rib" spring, without replacing the strain screw. The factory strain screw isn't long enough to properly tension the Wolff spring. If tightening the strain screw doesn't work then take the stocks off and look at the mainspring. If it has a large rib on the back and groove on the front it is a Wolff spring. Then replace it with a new S&W factory spring.

For some reason Woolf does not mention anywhere that the strain screw will be too short, and they don't furnish a longer screw with their Power Rib springs. Very poor practice!

 

[Seven High]

The first thing that I would do is disassemble the internals, then clean and lubricate the moving parts. YouTube can snow you how to properly disassemble it.

 

[JackM]

Check for cylinder end shake also. If the cylinder is moving forward to an excessive degree, misfires can result.

 

[Nomad Farrier]

Thank you all for the info, it was all very helpful. After examination with stocks off I found that the Strain screw was backed out a turn and half. I Burried that screw, checked to make sure it was oem spring, and now waiting for the ****ful Oregon rain to stop long enough to test it all out! I have to say that Im a member of another long range shooting forum and those guys are a bunch of sarcastic ******** to deal with. This forum is exactly the way a forum should work! All very positive and helpful comments!!
Merry Christmas!!!!

PS January 20th is what Im wanting for Christmas

 

[Retired W4]

Welcome to the forum from Hot Lanta. Make sure you read all the forum rules to keep from being dinged. The Big Gorilla (handejector) and his army of moderators run a tight ship.

 

[BC38]

The first thing that I would do is disassemble the internals, then clean and lubricate the moving parts. YouTube can snow you how to properly disassemble it.

Now that the strain screw is fully seated and you've confirmed that the hammer spring isn't a lightweight aftermarket replacement, if you still experience misfires, then a full internal cleaning would probably be the next thing to consider.

HOWEVER, if you aren't comfortable with a complete disassembly and cleaning, there is another alternative.

Find a container large enough to hold the revolver. Fill the container with a 50/50 mix of acetone and automatic transmission fluid. Remove the grips and submerge the whole revolver in the acetone & ATF solution for a few days. Then use an air compressor nozzle or a can of compressed air to blow into the hammer and trigger openings in the frame until no more fluid comes out. If the fluid is clean, you're done. If not resubmerge the revolver in the solution for a few days, blow it out again, and repeat this process as many times as necessary for the fluids coming out to be clear red (not black or gunky).

Once it is clean squirt some good gun lubricant into the trigger and hammer openings to lube everything up.

After this "flush" process, try shooting some more rounds through it and see if that solves the light-strike misfires issue.

 

[Alk8944]

1 1/2 turns loose for the strain screw is enough to take nearly all of the tension off of the mainspring! This should have been obvious by the very light pressure needed to cock the hammer in either single or double action!

You need to check all of the screws on any firearm periodically, and even if the gun is new! Screws vibrate loose even during dry-fire practice, not just live firing.