Revolver Mis-fire on slow trigger pull

[bilder]

I have a Hi Standard Sentinel MkII .357 revolver purchased at auction a couple years ago. I have never gotten around to firing it till this weekend and found a possible problem.

It will fire fine in single action, but in double action it tends to misfire with a slow trigger pull, but will fire fine with a quick trigger pull. Had 4 misfires out of 20 rounds. I was using FMC ammo.

Is anyone familiar with such an issue? Would it be related to the firearm or the ammunition?

Planning on taking it to a gunsmith when I have the time and cash to get it checked out.

[tailwind]

First thought, are you certain you are letting the trigger completely reset during 'slow' trigger pull?

[rbuck351]

See if you can measure the distance the trigger pulls the hammer back before releasing vs how far back it is when set by hand. I suspect it is not going back near as far by trigger pull. I don't know if you will be able to tell if a quick pull is bringing the hammer back farther or not but maybe by holding the gun in a vise and holding a piece of wood or such behind the hammer and doing the slow and fast pulls. I doubt it is an ammo problem.

[ADfields]

See if you can measure the distance the trigger pulls the hammer back before releasing vs how far back it is when set by hand. I suspect it is not going back near as far by trigger pull. I don't know if you will be able to tell if a quick pull is bringing the hammer back farther or not but maybe by holding the gun in a vise and holding a piece of wood or such behind the hammer and doing the slow and fast pulls. I doubt it is an ammo problem.

That was my first thought too but it doesn't make sense to me that a fast pull would draw it back more. I'm thinking it more likely that something is dragging, slowing down the hammer, sear or something rubbing with a slow pull. But when trigger is pulled fast everything clears and the hammer travels at full speed. I very much doubt it’s ammo but it’s always possible.

[BrownBear]

It's been a looooong time since I pulled apart a Sentinel, but odds are good that someone "tuned" the action by lightening the main spring one way or another. Your symptoms sound just right. Fast fire throws the hammer back a little further, so it comes forward with just enough extra oomph to pop most caps. Slow fire lets it drop a shorter distance and you get a click. Some caps like Remington small pistol are softer and might solve the problem if you're a reloader, but in the meantime I'd be checking around for a replacement main spring.

One other possibility, but less likely, is build up of crud in the action, especially on either side of the hammer body and on the pivot. Had it happen to me on a 629 I left rattling around under the seat of my truck for a year. Lint, hair, dirt and who knows what gummed up the action. In my case it resulted in a much heavier DA trigger pull along with failure to fire with mag primers. Easy fix with a good cleaning and lubing.

[bfrshooter]

It's been a looooong time since I pulled apart a Sentinel, but odds are good that someone "tuned" the action by lightening the main spring one way or another. Your symptoms sound just right. Fast fire throws the hammer back a little further, so it comes forward with just enough extra oomph to pop most caps. Slow fire lets it drop a shorter distance and you get a click. Some caps like Remington small pistol are softer and might solve the problem if you're a reloader, but in the meantime I'd be checking around for a replacement main spring.

One other possibility, but less likely, is build up of crud in the action, especially on either side of the hammer body and on the pivot. Had it happen to me on a 629 I left rattling around under the seat of my truck for a year. Lint, hair, dirt and who knows what gummed up the action. In my case it resulted in a much heavier DA trigger pull along with failure to fire with mag primers. Easy fix with a good cleaning and lubing.

This is correct. The mainspring is too weak. Double action has a shorter hammer fall.

[HUNTERKJL]

BrownBear, I think you nailed it. No need for further explanation/speculation by me as you described what is likely happening very well.