stumped ! - Gaining .5-.75lbs with side plate on

[alecmc]

did a little more work on a revolver of mine tonight, everything looks pretty good except one thing I cannot figure out.

When i test the trigger with a gauge with the side plate off I'm between 5.25-5.50 lbs , when I screw the side plate down it jumps up to 6 lbs or so.

I've looked for rough spots, rubbing, i've stoned the back of the side plate smooth, still the same thing.

are there any obvious things I should be looking for a newb like me not know yet?

[Dwight Stearns]

I would guess that the hammer pivot pin is flexing without the support of the side plate. Oh by the way, dry firing the revolver without the side plate in place is a good way to break the hammer pivot pin.

Dwight

[Toolguy]

That could be a lot of different things. It's pretty hard to say without seeing the gun. The first thing I would try is to take a flat file or stone and file across the hammer and trigger boss both at the same time. Those are a little higher than the rest of the sideplate. They are usually crooked on the surface. If you do both at once you will keep the file level.

File or stone the rest of the sideplate, working around the raised bosses to make sure there are no burrs for something else to catch on. You might look for rub marks on the hammer and trigger around their respective pivot holes.

Edited February 13, 2013 by Toolguy

[alecmc]

Thanks toolguy, i'll give that a shot tomorrow.

[Waltermitty]

I agree that you should avoid dry firing the revolver with the side plate off. The trigger and hammer studs are supported at the open end by the side plate. If the trigger stud flexes a little it could trip a fraction early.

As for what you need to do to get your trigger pull down below 6 pounds? The answer is on this board, it's up to you to match your situation up to your situation.

[Carmoney]

Nothing wrong with a 6-lb DA pull.

Go much lighter and you're going to start having troubles with either unreliable ignition or sluggish rebound anyway.

Besides, it's almost impossible to use a trigger gauge to measure a DA pull on a revolver.

[alecmc]

I agree nothing wrong with a 6lb pull, I just have a few other revolvers set at 5 lbs that work great, trying to keep a consistent weight across the board, I certainly know it's capable. Just wondering if I was overlooking something

[pskys2]

Almost sounds like something could be off square a bit. Have you tried some trigger and/or hammer pin shims? If they don't add anymore to the weight when you tighten the side plate then try shifting them from one side to the other. Trying to find a sweet spot in the Trigger, Hammer, Sear Rebound Block geometry.

I even took a squared hollow pin with a piece of 1200 grit sandpaper on it to smooth and square the trigger/hammer pin boss on the frame side and lightly stoned the side plate sides. But be careful if you go too far, you will have to shim them back up.

And of course with the pins flexing it can and will vary the pull. And increase the chance of breaking a pin. And it will happen.

[haras]

+ on the trigger and hammer pins. I had to send 2 back to S&W before I learned my lesson. Sheared those trigger pins right off.