Mainspring adjustment screw

[Archtop10]

If the revolver mainspring adjustment screw should be screwed in all the way tight as many posts suggest, to the point of trimming the end of the screw to do so, what good is having an adjustable screw? My EDC is a Model 19-3 nickel stubby. I was easily able to adjust the screw to the perfect spot that gives me a 8lb double action pull and a 3lb single action pull with zero push-off. Exactly how much material would I have had to remove from the screw tip in order to achieve the very same result?

And if I was so concerned that the screw might move by itself, that's why God created blue thread lock.
Just sayin'.

 

[Outpost75]

The purpose of the screw is to tension the leaf mainspring. The screw is backed off only to relieve strain on the spring to facilitate disassembly.

 

[Alk8944]

The purpose of the mainspring screw is to enable installation of the mainspring without it being under tension, it is not an adjustment. The spring is installed and the screw tightened to tension the mainspring. Any "adjustment" is done by the fitter at the factory by shortening the screw, if necessary, to achieve the correct "hammer lift" tension, the amount of pressure needed to initially begin cocking the hammer. After the initial fitting the mainspring screw is to be kept fully tightened!

If the screw is not fully tightened it will work loose due to vibration of the action and firing the gun! This will eventually result in failures to fire due to light hammer strikes. Except for late I-Frame and J-frame models with the coil mainspring this has been the standard S&W design since 1896. As a general rule virtually no guns had anything but flat and "V" springs at that time! The only coil springs in S&Ws werefor the bolt, extractor, rebound slide and locking bolt, where flat springs were not practical The cylinder stop coil spring was mostly only after 1905 or thereabouts.

 

[stansdds]

As previously stated, it is not an adjustment screw. The strain screw keeps tension on the main spring, backing the screw out relieves the tension so that the spring can be removed. As designed, the tension and pressure of the main spring is sufficient to ignite even military grade primers when the revolver is fired in double action mode. People will sometimes reduce the length of the screw so as to reduce the power of the spring, which may be perfectly fine for a target use only revolver, but may also result in a failure to ignite all primers when firing double action.

 

[bigggbbruce]

And if I was so concerned that the screw might move by itself, that's why God created blue thread lock.
Just sayin'.

Actually it was Dr. Vernon K. Krieble. Just sayin'

 

[413Maxwedge]

I used to have a "street rod" truck that would burnout and fishtail when I romped on it.
Should I loosen all the lugnuts on my new fwd car to get the same "loosey goosey" feeling?

Just kidding. As said, it's not an adjustment screw. Yes some people write about loosen it to "fine tune" the trigger pull but that is not a good idea unless you really know what you're doing. And not a good idea for a defensive gun.

I have done "trigger jobs" on most of my carry revolvers and adjusting the strain screw is not something I would do.

 

[ken158]

This has been discussed on many occasions but as noted, there is no "adjustment screw" on a S&W. The mainspring is designed to be tight for everything else within to operate as designed. If you feel you "must" do some alteration, then about 3 strokes with a file across the bottom of the screw is all that is recommended by the factory armorers.

 

[jcelect]

No one mentioned the trigger return spring! This spring has just about the same amount of effect on the trigger pull as the main spring. When making a change in the trigger pull you must make changes in both springs! Installing a "spring kit" is the best method of reducing the trigger pull on any revolver. Over time, may thousands of rounds, the main spring will have a tendency to retain an arch which will reduce trigger pull, a little, but it also reduces the hammer striking pressure. This can cause failure-to-fire rounds! Removing metal on any parts in not a good idea.

 

[Muley Gil]

No one mentioned the trigger return spring! This spring has just about the same amount of effect on the trigger pull as the main spring. When making a change in the trigger pull you must make changes in both springs! Installing a "spring kit" is the best method of reducing the trigger pull on any revolver. Over time, may thousands of rounds, the main spring will have a tendency to retain an arch which will reduce trigger pull, a little, but it also reduces the hammer striking pressure. This can cause failure-to-fire rounds! Removing metal on any parts in not a good idea.

Back before companies started selling spring kits, S&W would sell you a "target trigger return spring" that was about 14 or 15 pounds as opposed to the standard 18 pound return spring. It was intended to be used with the standard main spring.

 

[ken158]

No one mentioned the trigger return spring! This spring has just about the same amount of effect on the trigger pull as the main spring. When making a change in the trigger pull you must make changes in both springs! Installing a "spring kit" is the best method of reducing the trigger pull on any revolver. Over time, may thousands of rounds, the main spring will have a tendency to retain an arch which will reduce trigger pull, a little, but it also reduces the hammer striking pressure. This can cause failure-to-fire rounds! Removing metal on any parts in not a good idea.

Likely not mentioned because the OP was talking about the "adjustment screw" officially known as the mainspring! But - you are correct that the rebound spring also affects trigger pull. Maybe some of the matched aftermarket kits have perfected a 100% lighter pull function but as a dept armorer you would not believe what silly things someone will do to a revolver looking for the ultimate trigger pull.