How to lighten a triggerpull

[Billnpatti]

I have a lock that has a rather heavy trigger pull. The problem is that the full cock notch is too deep and the sear sets too deep in the notch. When you pull the trigger, you have to pull the sear out of the deep notch. This gives a heavy trigger pull. I have thought of two different remedies for this problem. First, I could file away the bottom of the full cock notch until it is just deep enough for the seir to set into it. This would require that I also file away part of the front edge of the half cock notch because the tumbler does not have a fly in it. The second remedy is to fill the full cock notch with a bit of metal to fill it out so the sear doesn't set so deeply into the notch. I could file down a piece of brass (because it is easier to work than steel) and use a tight fit and Super glue to fasten it into the full cock notch. By filling the full cock notch rather than filing it away, I don't have to file away any of the half cock notch. So, what do you suggest? Any better ideas? :idunno:

 

[rafterob]

I would file the full cock notch. It may not catch on the half cock during firing, I would just see how it goes. No biggy if you had to modify that some also. Just take real care when removing material because you can screw up a tumbler real fast.

 

[ron ward]

time after time this issue comes up and time after time it results in replies that demonstrate the confusion between trigger pull weight and engagement depth....the two are not the same and are only related because of the misunderstanding.
the pull weight is not a product of engagement depth alone, it is a product of sear angles being incorrect and the depth of engaement. if the sear angles are correct, the length of engagement does not increase the pull weight, it only increases felt trigger drag that is misinturpreted as a heavy pull because you have to pull on the trigger long enough to drag the sear out of the notch. a shallower engagement will feel lighter because the pull time is shorter, but it is infact the same weight at the instant of release.
proper sear engagement geometry calls for the engaement angles to be at right angles to a line drawn through the tumbler and sear pivot centers. when this supposedly perpendicular line is actually greater than 90degrees, the sear has to lift the tumbler against the main spring's tension to disengage the sear from the tumbler's nothch. it is this lifting that makes the triggers weight physicly higher. of course, the deeper it's engaged, the more it must rotate the tumbler against the mainspring and the harder it will be to pull the trigger. with a correction of the sear agles, all a shallower engagement will do is bring the trigger's starting pull weight closer to the release weight. if you don't have that felt increase in pull weight, you are tricked into feeling a weight reduction when in fact there is no weight reduction at all.
some amount of safety is gained by having the sear angles greater than 90 degrees and the manufacturers use this to satisfy product liability concerns.
proper sear angles will give you a trigger that is light and crisp and will be neutral in that it will not want to jar off or stay engaged. it should be done with fixtures that hold the sear and trigger's engagement faces in the correct position as they are honed to the correct angles in relation to thier installed and working position in the lock. this should be done by a competent gunsmith that understands trigger geometry.

 

[matt denison]

time after time this issue comes up and time after time it results in replies that demonstrate the confusion between trigger pull weight and engagement depth....the two are not the same and are only related because of the misunderstanding.
the pull weight is not a product of engagement depth alone, it is a product of sear angles being incorrect and the depth of engaement. if the sear angles are correct, the length of engagement does not increase the pull weight, it only increases felt trigger drag that is misinturpreted as a heavy pull because you have to pull on the trigger long enough to drag the sear out of the notch. a shallower engagement will feel lighter because the pull time is shorter, but it is infact the same weight at the instant of release.
proper sear engagement geometry calls for the engaement angles to be at right angles to a line drawn through the tumbler and sear pivot centers. when this supposedly perpendicular line is actually greater than 90degrees, the sear has to lift the tumbler against the main spring's tension to disengage the sear from the tumbler's nothch. it is this lifting that makes the triggers weight physicly higher. of course, the deeper it's engaged, the more it must rotate the tumbler against the mainspring and the harder it will be to pull the trigger. with a correction of the sear agles, all a shallower engagement will do is bring the trigger's starting pull weight closer to the release weight. if you don't have that felt increase in pull weight, you are tricked into feeling a weight reduction when in fact there is no weight reduction at all.
some amount of safety is gained by having the sear angles greater than 90 degrees and the manufacturers use this to satisfy product liability concerns.
proper sear angles will give you a trigger that is light and crisp and will be neutral in that it will not want to jar off or stay engaged. it should be done with fixtures that hold the sear and trigger's engagement faces in the correct position as they are honed to the correct angles in relation to thier installed and working position in the lock. this should be done by a competent gunsmith that understands trigger geometry.

Good post, especially the last sentence.

 

[crockett]

It sounds like you have a simple trigger rather than a set trigger. If that is the case you have to imagine the trigger as sort of a carpenter's square, one leg is the trigger your finger presses against and the other "leg" is the portion that pushes up against the sear. As stated the depth issue relates somewhat more to a creepy trigger, etc. The only way I know of to lighten the trigger pull is to install a different trigger where the trigger is pinned in place with the pin much higher that exists in a trigger pinned to tabs on a trigger plate. This has been discussed before and should be in the achives.
The other option is to make a "hair trigger" which might not be safe but one method with modern arms is to drill a hole in the notch and install a drill rod and then file that down. You are supposed to soft solder it but I don't see why a good epoxy glue won't work as well.

 

[LRB]

Don't file the notch down, that is asking for trouble. Glue or solder a piece of steel behind the notch which will regulate the engagement of the sear as you were thinking to do. Also lighten the sear spring. These two changes combinined will give you a much better pull. The sear spring only needs enough strength to return the sear in a positive manner.

 

[Billnpatti]

Thanks for all of the great input. Today, I honed the full cock notch and the trigger sear to get rid of some roughness. This made the trigger a bit smoother but it is still pretty stiff. I may have to send it off and have a muzzleloading gunsmith work on the sear engagement angle. There are several good ones out there so I will just have to pick one and send it to him. :thumbsup:

BTW, Wick, how do I lighten the sear spring? I guess I could compress it with some pliers but I am afraid of breaking it. What's the secret?

 

[Jason Lewis]

put the sear spring in a vice and file the long part of the spring, do not file on the bend or you will break the spring. it's pretty easy. file a little then put back together and check to see if it's lighted up any.

 

[LRB]

Thats about it. Or you can grind it down, very slow and careful to not over heat.

 

[ron ward]

sear spring weight is something to look at when you are trying to get the last the few ounces of an already well tuned trigger pull off. most springs ends are so close to the sear pivot that you can't tell the few extra ounces of pull weight from the spring untill the rest of the system is right. concentrate on getting the sear/tumbler geometry correct and engagement depth decent and i'll bet the sear spring pressure will suddenly disappear all by itself. the closer to the pivot the spring's end is, the less you will feel it's contribution to pull weight. it is easily over come by you finger because it's movement is so small. in fact, you want a fairly agressive searspring for the above reason.... it is actually the spring that should be relied on to keep the sear engaged when the tumbler/sear geometry is correct because it is supposed to be set real close to the sear's pivot so that a strong spring's positive engagement can be easily overcome when the trigger is pulled. a properly tuned and polished neutral sear/tumbler geometry will require very little weight to disengage and the sear spring's weight becomes the main character in the lock's reliability to stay engaged, not the fact that the sear/tumbler angles are locking them together.
when set up this way, because of the sear spring's shorter legs they are less affected by jarring off ans the lock is therefore more reliable.
some where along the time line it was decicded that it was easier to make the sear/tumbler angles such that the tumbler would have to be rotated aginst the mainspring to diengage them and it slowly became the accepted method to cheaply get reliability in mass production .....shortcuts! the problem with that, is that as quality control will get sloppy in high production, the angles tend to drift in favor the "heavy pull" aspect and we end up with 6 and 7 plus pound triggers on our factory guns.
i would venture to say that even the well known high quality lock makers have more sear angle in them than is needed....they too, have to cover thier butts with the underwriters, even more so...

 

[Billnpatti]

Well, gentlemen, I considered all of the advice that was offered and in the end, I glued a piece of brass into the full cock notch, honed the full cock notch and the sear with an ultra fine stone to a glass-like finish. I didn't touch the spring. I ended up with a trigger pull of around 3 to 4 pounds and a glass smooth trigger. It is sa-weet. Every time I snap that trigger (flintlock) I feel like I need to lay my rifle down and do my happy dance......I don't, it ain't pretty.

 

[ron ward]

i'd do the dance anyways....beuty is in the eye of the beholder....just make sure there aint no beholders around! :thumbsup:

 

[fatboy]

Sounds like you had good success I was told once to try JB Weld for what you did never had a need to try it myself.