SEAR SPRING

[APG]

So I've been looking to reduce the trigger pull on my Pedersoli 1861 Springfield. Think it's about 15+ ponds right now . I know that normal for military rifles of that era. Looking at reducing the pull by reducing the sear spring tension a little. Would filling down the width of it some be an acceptable way of doing this? A little at a time so that it doesn't become to weak to do it's job. What do you guys think?

 

[Phil Coffins]

Start by making sure the sear and tumbler are engaging correctly and have smooth surfaces. Look how the sear spring is bearing on the sear, it should be close to the screw. After all that then consider the spring.

 

[billraby]

How heavy is the trigger pull with the gun uncocked? That is the resistance you are getting from the sear spring. By cutting down the sear spring you can remove about half of that weight. It is probably not very much. Most likely the problem is caused by how the sear and tumbler fit together.

 

[rich pierce]

Great advice above. After checking those things, and others (make sure nothing is binding in the lock, that the sear bar is free to move in its inlet, and the trigger bar is free to lift the sear bar quite far) yes, the spring can be thinned. It’s unusual to reduce the width because you want to maintain a good bearing surface of the sear spring tip on the sear arm. So, thinning is done but must proceed very slowly with frequent testing. A 25% reduction in thickness will result in a 43.75% decrease in force, because strength is equal to the square of the thickness. (It’s 3/4 as thick now and the square of 3/4 is 9/16, and 9/16 = 0.5625, so it’s now 56.25% as strong as it was)

If you made it half as thick it would only be 1/4 as strong as it is now.

You can’t add metal back.

 

[FlinterNick]

If its a pedersoli Springfield, the replacement drop in sear springs are usually not that strong. Try Dixie Gun Works or VTI gun parts.

Otherwise one way to reduce the spring tension is to hit the spring with a fine grit belt sander, 320-400 grit. Use low pressure its on the sander and test the spring out, if you don’t have a belt sander, then you’d an use a Dremel sanding drum or cross cut file, however you’ll likely need to polish off the file marks.

 

[APG]

Well that took a long time but it worked very well. After double checking all the surfaces of the sear and tumbler and everything else on the lock to include the trigger assembly I found them all to be in good working order. At least what my totally untrained and fuzzy vision e eyes could see. I went ahead and filled the sear spring down very slowly and carefully checking it along the way. Gotten trigger pull down further than I thought it would go. It's about 7-8 pounds pull. Can't wait till next time I shoot it.

 

[APG]

I'm at the range today and I'm pleased with the results of filing the search spring down to reduce the trigger pull. At first I thought it was reduced to 7 or 8 pounds but checked it here and it's closer to 4-5 pounds. Good times.

 

[Artificer]

I don't wish to rain on your parade, but thinning down the sear spring will not make such a significant reduction in trigger pull all by itself. You can thin/reduce that spring all you want and it will only result in 1/2 lb to at the very most a 1 lb reduction in trigger pull weight and the latter pretty much only if you are using an Original Sear Spring from the period. Repro Sear Springs don't give the resistance the Original Springs do. Something else has to be going on because normal trigger pulls for M1861 Springfields are normally 10 to 12 pounds, IF they even somewhat closely follow the original lock design.

BTW, when I write about trigger pulls, I'm referring to using NRA approved trigger pull weights to check. This is what the North South Skirmish Association uses as well as all the major shooting competitions that have minimum trigger pull weight requirements.

Gus

 

[LRB]

Well that took a long time but it worked very well. After double checking all the surfaces of the sear and tumbler and everything else on the lock to include the trigger assembly I found them all to be in good working order. At least what my totally untrained and fuzzy vision e eyes could see. I went ahead and filled the sear spring down very slowly and carefully checking it along the way. Gotten trigger pull down further than I thought it would go. It's about 7-8 pounds pull. Can't wait till next time I shoot it.

Sear springs on nearly all production locks and actions whether original or modern are commonly overpowered with some being much overpowered and DO make a significant contribution to trigger pull. Lightening that spring is a good place to start but not necessarily the cure all. Lightening that spring also quiets actions and reduces unnecessary wear. A sear spring needs only enough power to reliably, safely, and positively reset the trigger after release. Military firearms are intentionally produced with heavy trigger pulls for the sake of safety in battle when fingers can be very nervous. Mainsprings also contribute to the trigger pull weight, but much thought and caution should be considered before lightening that one. Especially with flintlocks, but also with the rest. You must have reliable ignition whether muzzleloader or modern.

 

[Phil Coffins]

APG, you done good.

 

[APG]

I don't wish to rain on your parade, but thinning down the sear spring will not make such a significant reduction in trigger pull all by itself. You can thin/reduce that spring all you want and it will only result in 1/2 lb to at the very most a 1 lb reduction in trigger pull weight and the latter pretty much only if you are using an Original Sear Spring from the period. Repro Sear Springs don't give the resistance the Original Springs do. Something else has to be going on because normal trigger pulls for M1861 Springfields are normally 10 to 12 pounds, IF they even somewhat closely follow the original lock design.

BTW, when I write about trigger pulls, I'm referring to using NRA approved trigger pull weights to check. This is what the North South Skirmish Association uses as well as all the major shooting competitions that have minimum trigger pull weight requirements.

Gus

Well I filed down the search spring on my Pedersoli 1861 Springfield and the trigger pull went from a stiff 15 pounds down to about 5 pounds. So that about 10 pounds lighter than before.