Haven’t read through entire thread but enough to see you’re already getting sound advice
I’ll only add this link to a great article ... Improving the trigger on Smith & Wesson Revolvers: https://straightshooterjake.blogspot.com/p/revolver-springs.html
Expressly because it includes this section ...:
<snip>
2.2.3 Issues which cause light strikes
The number one cause of light strikes and misfires is a weak hammer strike. This point cannot be overstated. Most of the time when people have misfires, it is because the mainspring tension is insufficient, and the hammer is not hitting hard enough. Low mainspring tension may be caused by either a weak mainspring, or by a loose or improperly fitted strain screw. You can find more information about mainspring tension in the section on working with mainsprings and the strain screw.
However, there are also mechanical problems which can contribute to light strikes. If these mechanical issues are just slightly out of spec, the revolver will often work reliably with a strong mainspring. But if tolerances are too far off, then you may get misfires even with a very strong spring.
The descriptions below illustrate some of the mechanical issues which can cause light primer strikes. A complete description of how to check all of these areas is beyond the scope of this article. But you should be aware that a qualified gunsmith will check most of these areas while doing a trigger job, and most of these tolerances can be checked quite quickly. You can find more information about these issues in the references section of this article.
Firing pin length and protrusion
You may get light strikes if the firing pin does not protrude far enough through the breech face. On guns which have a frame mounted firing pin, the overall length of the firing pin also needs to be sufficient. There is more information about firing pins in the appendix.
Endshake
Endshake is the amount that the cylinder can move forward and backward. If there is too much endshake, then the cylinder can move forward when the firing pin strikes the cartridge. This movement can use up energy that should have been delivered to the primer.
Headspace
Headspace is the distance between the back of the cylinder and the breech face. If there is too much headspace, then the cartridges may be too far from the firing pin. On Smith & Wesson revolvers, the headspace is also called the "rear gauge."
Friction and interference
Excessive friction on the hammer or the firing pin can reduce the energy of the firing pin strike. Interference between the hammer and the edge of the frame can also drain power from the hammer.
Off center strikes
Primers are most sensitive in the center of the primer. If the firing pin strikes are off center, then a very strong strike may be required to get reliable ignition.
<un-snip>
I’ll only add this link to a great article ... Improving the trigger on Smith & Wesson Revolvers: https://straightshooterjake.blogspot.com/p/revolver-springs.html
Expressly because it includes this section ...:
<snip>
2.2.3 Issues which cause light strikes
The number one cause of light strikes and misfires is a weak hammer strike. This point cannot be overstated. Most of the time when people have misfires, it is because the mainspring tension is insufficient, and the hammer is not hitting hard enough. Low mainspring tension may be caused by either a weak mainspring, or by a loose or improperly fitted strain screw. You can find more information about mainspring tension in the section on working with mainsprings and the strain screw.
However, there are also mechanical problems which can contribute to light strikes. If these mechanical issues are just slightly out of spec, the revolver will often work reliably with a strong mainspring. But if tolerances are too far off, then you may get misfires even with a very strong spring.
The descriptions below illustrate some of the mechanical issues which can cause light primer strikes. A complete description of how to check all of these areas is beyond the scope of this article. But you should be aware that a qualified gunsmith will check most of these areas while doing a trigger job, and most of these tolerances can be checked quite quickly. You can find more information about these issues in the references section of this article.
Firing pin length and protrusion
You may get light strikes if the firing pin does not protrude far enough through the breech face. On guns which have a frame mounted firing pin, the overall length of the firing pin also needs to be sufficient. There is more information about firing pins in the appendix.
Endshake
Endshake is the amount that the cylinder can move forward and backward. If there is too much endshake, then the cylinder can move forward when the firing pin strikes the cartridge. This movement can use up energy that should have been delivered to the primer.
Headspace
Headspace is the distance between the back of the cylinder and the breech face. If there is too much headspace, then the cartridges may be too far from the firing pin. On Smith & Wesson revolvers, the headspace is also called the "rear gauge."
Friction and interference
Excessive friction on the hammer or the firing pin can reduce the energy of the firing pin strike. Interference between the hammer and the edge of the frame can also drain power from the hammer.
Off center strikes
Primers are most sensitive in the center of the primer. If the firing pin strikes are off center, then a very strong strike may be required to get reliable ignition.
<un-snip>
