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.