66-1 6” shot yesterday…small issue

[Model29-26.5]

Shot my 66-1 for the first time yesterday.
It wouldn’t always fire. Maybe 15% of the time it would make a small dent in the primer but not deep enough.
I tightened the main spring a little when I got it home figuring this should solve it.
I haven’t experimented with main spring yet but I figure it’s a balance between getting the lightest trigger pull you want and the hammer not quite having the potential energy behind it to hit the primers if it’s too light?
Is there some kind of rule of thumb with this?
Thanks

 

[38 Specialist]

I had the exact same problem with the gun I bought some months back. The gunsmith at the shop opened it up and said that the main spring was worn out. I replaced it myself with a wolff spring kit and it performs perfectly.

The gunsmith said a lot of competition shooters will set up their gun with a very very light trigger. They used cartridges that use Federal primers. These, so he said, ignite with little force. Using other ammo, there are likely to be light strikes..

 

[stansdds]

Presuming the action is clean, properly lubricated, and everything is moving smoothly, the most common causes of light strikes would be:
The strain screw not being fully tightened
The strain screw being shortened, which is a method of getting a lighter trigger pull.
The factory main spring was swapped out for an aftermarket spring, which is a method of getting a lighter trigger pull.
Possibly a combination of the above.

 

[Model29-26.5]

There was plenty of torque/thread left on the strain screw. Still is. I gave it a turn or two.
Hopefully should do the trick.
I feel a little bit of difference in the pull.
If it was missing most of the time I’d have figured it needed more but it was about one miss each cylinder or so.
I just wondered if there’s any rule of thumb when it comes to setting the main spring tension?

 

[StrawHat]

S&W says the strain screw should be screwed in tight. As an armorer, I agree. Screw it in tight and quit messing with it. If the action is too stiff to use, have someone perform action work on the revolver. My competition revolvers all had work done on them. My carry revolvers, maybe. But ALL of them have the strain screw in tight.

Kevin

 

[Model29-26.5]

S&W says the strain screw should be screwed in tight. As an armorer, I agree. Screw it in tight and quit messing with it. If the action is too stiff to use, have someone perform action work on the revolver. My competition revolvers all had work done on them. My carry revolvers, maybe. But ALL of them have the strain screw in tight.

Kevin

Thanks! Easy.
This one was not at all tight.

 

[Protocall_Design]

If the strain screw isn't tight, it will gradually work it's way out as the mainspring flexes during use. The hammer strike gets lighter and lighter, with more and more misfires.

As mentioned above, the type of primers in the ammo is a critical part of the equation. Federal is the easiest to set off, Winchester is a close second, everything else needs a pretty solid hit.

Main causes of misfires are - Mainspring set too light for primers in use, firing pin too short (a short firing pin will still work with a heavy blow), most factory ones are under the .495 minimum, cylinder end shake, too much headspace.

You can take pounds off of the trigger pull by using a lighter rebound spring. Get the mainspring set to fire 100%, then find the lightest rebound spring that returns the trigger in a positive manner. The factory one is generally thought to be 18 lb. Wolff sells them from 11 lb. to 16 lb. in one lb. increments.

You can weigh the amount of tension the mainspring is putting on the hammer by using a trigger pull gage on the hammer instead of the trigger. This will tell you what any changes you make are doing, rather than just guessing at it. You have to pull the trigger and hold it back so the hammer is free from any trigger influences.

 

[Model29-26.5]

Thanks folks. All great info.

 

[Vtgw938]

Back in the day when carrying a revolver on duty you wanted the strain screw all the way tight and no replacement rebound spring or main spring. You didn't want a failure to fire and you wanted the trigger to positively rebound into position without any hesitation. Shooting for fun, we can play with all these things but for business, screwed tight and bone stock springs are the way to go IMO.

 

[USBP SW]

Back in the day when carrying a revolver on duty you wanted the strain screw all the way tight and no replacement rebound spring or main spring. You didn't want a failure to fire and you wanted the trigger to positively rebound into position without any hesitation. Shooting for fun, we can play with all these things but for business, screwed tight and bone stock springs are the way to go IMO.

Not only do you not want any failures, which would always happen at the worst possible time but there was always the possibility that an enterprising attorney would find out that you had altered your revolver, lightened the trigger pull, making it more dangerous.
An individual in management had a misfire during qualifications, I examined the revolver and found that it had been altered for ppc shooting, the rebound slide spring was cut and the strain screw shortened. I deadlined the revolver and issued another, I was not a friend of management that day but my coworkers were certainly entertained.

 

[shawn mccarver]

Shot my 66-1 for the first time yesterday.
It wouldn’t always fire. Maybe 15% of the time it would make a small dent in the primer but not deep enough.
I tightened the main spring a little when I got it home figuring this should solve it.
I haven’t experimented with main spring yet but I figure it’s a balance between getting the lightest trigger pull you want and the hammer not quite having the potential energy behind it to hit the primers if it’s too light?
Is there some kind of rule of thumb with this?
Thanks

The strain screw is NOT an adjustment or a balance between light trigger pull and the energy to ignite the primer.

The strain screw is to be screwed all the way down until it seats. Otherwise, it can work loose and cause a failure to fire. I suppose that is OK on a range toy or competition gun, but NEVER ok on a gun used for defense.

Tighten the strain screw all the way down as it is engineered and intended by the factory.

 

[Model29-26.5]

The strain screw is NOT an adjustment or a balance between light trigger pull and the energy to ignite the primer.

The strain screw is to be screwed all the way down until it seats. Otherwise, it can work loose and cause a failure to fire. I suppose that is OK on a range toy or competition gun, but NEVER ok on a gun used for defense.

Tighten the strain screw all the way down as it is engineered and intended by the factory.

Thanks. Good to know

 

[toad67]

Or maybe it's had a steady diet of 38's and just needs a cylinder cleaning..

 

[Model29-26.5]

Nah. That strain screw was a long way out.
I tightened it all the way in just now. Several turns and I could see the diff.
I’m sure that fixed it

 

[Vtgw938]

I've handled revolvers that had the screw turned out so much that it will actually bind the action. I assume because the spring is too straight with no bend.

 

[ken158]

When I was at the armorer’s school, the instructors admitted the strain screw was the downside of the revolver’s design. They had countless stories of warranty repairs fixed by tightening the screw as it is designed. If something is easily accessible, guys are gonna turn screws and take it apart. I always check the strain screw before I ever try to duplicate a reported problem.

 

[stansdds]

Nah. That strain screw was a long way out.
I tightened it all the way in just now. Several turns and I could see the diff.
I’m sure that fixed it

That probably did fix the light strike issue, but there is only one way to know for certain. Go back to the range with the same ammo that you used the previous time and test it. Once you do that, you will know for certain. Please let us know how it goes.

 

[Bald1]

That gun is a lemon. Unsafe and an accident waiting to happen. Ship it to me and I will “ properly “ dispose of it

 

[gwpercle]

You want the gun to fire ... every time , 100% .

If it doesn't do this when the screw is fully tightened and / or you want a lighter trigger pull ... I take mine to a local gunsmith who does a reliability and trigger job on them . See if you can find someone ...
If you are in Louisiana the name is Clark Custom Guns ... they do first rate handgun work .
Gary

 

[Model29-26.5]

You want the gun to fire ... every time , 100% .

If it doesn't do this when the screw is fully tightened and / or you want a lighter trigger pull ... I take mine to a local gunsmith who does a reliability and trigger job on them . See if you can find someone ...
If you are in Louisiana the name is Clark Custom Guns ... they do first rate handgun work .
Gary

I’m sure it’s fine now.
I’m not worried about the pull.
The strain screw was quite a way out.
It took several turns to get it all the way in.
I’m sure that was the issue.