Adjusting trigger pull weight

[Darkgael]

I have a pistol which has a wildly heavy trigger. Has to be more than 20 lbs. The lock is pictured. Which spring needs to be adjusted in order to lower the trigger pull weight?

 

[Are. M.]

https://www.muzzleloadingforum.com/threads/flintlock-trigger-pull-help.124874/#post-1717333
Zonie has a lengthy reply about 4 posts down. I'm sure the information will translate to your percussion lock.

I worked on my sear spring a lot, polished the tumbler sear notch and sear. It helped on my Pedersoli Kentucky pistol. A buddy of mine took metal off his mainspring and it lightened his up considerably. Went from 12-15lbs (not kidding) to between 3-5. Mine is still hovering around 8.

 

[No second place]

"Has to be more than 20 lbs"... If you measured 20pds on your trigger guage your springs are not likely your only problem. Notched instead of flat sear and binding . Before grinding springs, remove them to manually work trigger both in and out of gun to check for binding issues...c

 

[Darkgael]

Thanks for the link to Zonie and the advice. I will use both. Very helpful.

 

[M. De Land]

I have a pistol which has a wildly heavy trigger. Has to be more than 20 lbs. The lock is pictured. Which spring needs to be adjusted in order to lower the trigger pull weight?

Lightening a main and trigger spring is not always the best solution for trigger pull reduction and can some times lead to misfires and hammer blow back. Usually the best route is to first check engagement interfaces to make sure they are square and plum with each other. There should be no hammer movement at all before the sear disengagement from full cock regardless of what you hear.
A sear lift is the best method I have ever found to reliably lesson trigger pull without sacrificing any safety or hammer fall force. I like to reduce trigger spring weight while keeping it strong enough to be reliable in cold weather but I like to leave main springs alone if possible except to dress the corners and bend back to prevent fatigue cracking.
Weight if under five pounds is not really the most important part of setting up a good trigger pull. A very good trigger of 3 pounds if crisp and no over travel can be handled by most any one even on a hand gun. Having said that I usually like mine at about 1.5 lbs with a clean break and no noticeable over travel. After any good trigger job the lock should not be able to be knocked off full cock by any sharp blow to the trigger guard, lock or barrel.
Hear is a sear lift on a rifle of mine keeping the full mainspring weight. It is well under 3 lbs and breaks cleanly.
Notice in the side view the lift limits the engagement of the sear. This is what reduces the trigger weight and sear movement for a clean (creep free) trigger break . These can be set up and used on hand gun and rifle alike.
Click on picture to enlarge.

 

[Darkgael]

I took the advice that was tendered. It worked. Trigger down to about 8lbs. The gun is useful now.
Thank you for the advice.

 

[M. De Land]

I took the advice that was tendered. It worked. Trigger down to about 8lbs. The gun is useful now.
Thank you for the advice.

My guess from your description is the sear and full cock notch need to be stoned square and plumb to each other and the edge broke to finish up. If the angle of engagement is to acute then the sear has to push the hammer back to release from full cock and if off angle in the opposite direction than the gun can be pushed or bumped off from full cock. If the angle is correct and full contact is made from side to side across the sear face then the hammer will not move through trigger let off and will not be able to be knocked off by impact.
Sear/hammer notch stoning needs to be done by some one with experience and the proper jigs and stones to accomplish this correctly to wind up with a safe, long lived and efficient job.