Help with a Smith and Wesson Model 66-2 issue.

[UncleEd]

I keep betting, hoping, that all is needed is for the gunsmith to put in
new springs from a kit and all will be well; that the parts were not
butchered by the previous owner. Good luck, Zelwood.

 

[halfmoonclip]

The sold you a potentially dangerous gun...if they can fix it, fine, you're golden.
If not, offer them $250 out the door, as is, no liability on their part.
Even if they want to haggle, you may still get a better deal. How badly do you want the gun?
Moon

 

[MrBorland]

My own measure, after tinkering with a Smith, is to dry fire it as fast as I can. If I can beat the trigger, time to go back in with a heavier rebound spring. It depends on lots of things, including the slickness of the inner works.

It's an interesting philosophic question:

I've maintained the rebound and main springs should be balanced, but what is "balanced"? I've established that metric myself by measuring the DA & SA pull weights on stock revolvers and concluding the springs are "balanced" when the DA:SA ratio is roughly 2.8:1. You can swap springs for a lighter pull (and I have), but the ratio remains the same.

OTOH, the issue with an imbalanced rebound spring is the reset, so a functional way to establish balance is whether you can beat the reset. If you can, for whatever reason, put a heavier rebound spring in.

I keep betting, hoping, that all is needed is for the gunsmith to put in
new springs from a kit and all will be well; that the parts were not
butchered by the previous owner

If the OP is experiencing pushoff, it ought to be fixed, of course. OTOH, the OP also indicated the SA & DA pull weights are 5 oz and 4lbs, respectively, yet the gun shoots reliably. Assuming the measurements aren't off, the gun might be the product of an outstanding gunsmith who really know what they were doing.

hmmm....coming back to the aforementioned DA:SA ratio of 2.8:1: The OPs SA & DA pull weights of 5 oz and 4lbs, and that ratio is more like 13:1. The reliability and the pushoff could be explained simply by an uber-weak rebound spring. With an appropriate rebound spring, the SA and DA would come up quite a bit, yet it's the mainspring, which wouldn't change, which provides the power to the falling hammer. As far as the pushoff, the trigger sear is engaging the hammer notch by a cat's whisker. If the rebound spring is way too weak, there may be too little resistance to rolling the trigger clockwise (looking into the open lockwork from the right), resulting in pushoff. Maybe all it needs is a heavier rebound spring? A spring that gets SA to roughly 3lbs, ought to take DA to roughly 8lbs (DA:SA = 2.7:1) - I'd be interested to see what effect that has on pushoff, if any.

 

[halfmoonclip]

A double action weight of 4 lbs? Color me skeptical that it is really that light, as well as a 5oz single action. Too light, really silly light springs may indeed be the source of the OP's problems. A stouter rebound spring may stop the push off issue completely.
Measuring trigger pull is no small task; to really be done right, it should involve progressively heavier weights on a rod suspended on the trigger. Our late range officer was a master of this, and Bullseye guys were real fusspots on the subject. I've had relative success holding the gun in a leather jawed vise, and pulling against the trigger with a spring scale. A stiff breeze should put off a 5oz trigger.
In any case, I've had Smith revos with a superb single action break, and lousy double action. The converse has also been true. Yes, the springs must be in balance, but a lot of that is based on feel, not mathematics...IMHO.
Moon

 

[MrBorland]

Maybe all it needs is a heavier rebound spring?

Too light, really silly light springs may indeed be the source of the OP's problems. A stouter rebound spring may stop the push off issue completely

the strain screw was a little loose. I tightened it, two or three turns which only resulted in causing the trigger to fail to return to the forward position on it's own.

I did take the gun to the range and it had no issues with any type of failures to fire

If it's reliable, but with poor reset, as the OP related, I suspect the mainspring is fine. I'm curious to see what that rebound spring looks like. At 5oz, maybe someone used a spring from a Bic pen?

 

[Zelwood]

So, I picked the gun up yesterday. They replaced the rebound spring and stoned the engagement surfaces. The issue of being able to push the hammer forward when cocked seems to have been fixed. So has the issue of the trigger failing to return to the forward position. Additionally, I now have a trigger pull of about 7 1/2 pounds in double action and 1 1/2 pounds in single action. A little lighter than I would have liked in SA but acceptable. There was no charge for the work. I have not shot it yet but will soon. Thank you to everyone who responded to this post.

 

[UncleEd]

So, pretty much as expected though perhaps a little
stronger trigger return spring might be appreciated
even after the "fix."

 

[IWAC]

I recently purchased a Smith and Wesson Model 66-2 with a 4-inch barrel. When measured with a Lyman digital trigger gauge I have an average double action pull of just over 4 pounds and a single action pull of about 8 ounces. The issue is that when cocked, forward pressure on the back of the hammer of about 2 pounds will cause the hammer to fall. The general consensus of the people who have handled it is that either some work was done to lighten the trigger or there is something damaged internally. If I knew what had to be replaced or modified, I could probably do it myself with the help of a video. However, I am not as confident in my ability to diagnose the problem. What would be the most likely components that were damaged, replaced or modified to result in this issue? I like the 4-pound double action pull and could live with the 8-ounce single action pull but would prefer if it were a little heavier. I do have concerns about the fact that I can just push the hammer forward. Thanks

Great gun! But needs the immediate atttention of a qualified gunsmith! Both trigger pulls are waaaay light for safe shooting, IMO!