Has anyone... Weakened trigger pull on a Sharps '74 single trigger

[Thomas (Tom) Horn aka James Hicks]

In regards to a Sharps '74 SS in caliber 45-70 rifle single trigger whether long rifle or the Cavalry model.   Has anyone tried reducing the heavy trigger pull?  I have a Sharps '74 Cavalry Carbine (Armi Sport Chiappa) and the trigger pull is well over 10.5 lbs.  That is WAY too heavy a pull for accurate shooting.  After removing the Lock Plate and looking at the Main Spring which is also the Trigger Spring it is a VERY THICK SPRING... any suggestions on HOW TO REMOVE the spring would be appreciated.  I know how to weaken it, but removing the spring is a different story. Owners manual does not state HOW TO disassemble the Lock Plate. One person told me he removed metal from his spring for weakening the trigger pull and it did not help.  Any suggestions would be appreciated. Thanks in advance.

[Blair]

Tom,

A main spring vice is very important tool to have on hand.
I prefer to have two main spring vices for doing any lock work.
One to help remove the spring in the lock and the other to help compress any new spring I might want to use.
Just my suggested opinion. Hope this helps.
My best,
Blair

[Kent Shootwell]

With the lock removed full cock the hammer then place your main spring vice on the spring and tighten a bit. Hold the lock and hammer and release the sear and lower the hammer. The spring can be lifted off the lock plate and unhooked from the stirrup. Check the sear and tumbler for proper engagement before working the spring, it maybe half your problem. Check for drag marks from the sear and spring on the plate.

[Thomas (Tom) Horn aka James Hicks]

I wish to thank Blair and Kent for the response...much appreciated.  I will follow thru.  I thank you for the timely response.

[Blair]

Tom,

Keep in mind the Mainspring on a Sharps also has the sear/trigger spring built into it.
You need to be careful in how you place the mainspring vice so that vice does not damage or brake the sear/trigger spring portion of the mainspring.
My best,
Blair

[Thomas (Tom) Horn aka James Hicks]

Blair-

I found that out... do not ask me how I learned that.... but all is not lost... I had previously ordered two extra Main Springs just in case... laughing

[Blair]

This is some information that Two Flints may like to add to the SSS forum because the mainsprings are so similar to the Spencer's

My recommendation for lightening the trigger pull on a single trigger Sharps or Spencer is... first buy a new tumbler cut for a fly and, of course the fly. (this option is available within most of the repro arms of this type today)

Now you can shorten the length of travel the sear has in the full cock notch without the sear hanging up on the half cock notch during the Hammer fall.

The other method is to drill and tap a small hole for a set screw just the rear of the full cock notch on the tumbler.
This can be a very "IFFY" operation depending on the hardness of the tumbler in that area. However, the set screw can be adjusted, in or out, to help increase or ease the trigger pull, respectively.
I hope this info helps.
My best,
Blair

[Thomas (Tom) Horn aka James Hicks]

Blair-

Thanks for the additional... I read about that somewhere, about putting a small screw in the tumbler... that is more than I wish to travel.  I will try weakening the spring to get the desired amount of trigger pull.  I have on hand EXTRA SPRINGS in case I remove too much.  I am more experienced with removing metal to weaken a spring versus that other "iffy" proposition.  Thanks for mentioning it.  My best to you.

[cheatin charlie]

I have an 1859 Sharps I would like to lighten the trigger pull on could you post some pictures of your spring when you get done?

[sail32]

Try any of the Flintlock muzzle loading forums.

The gun building sections should be able to help as the Sharps lock is just a updated flintlock lock.

[Blair]

Please keep in mind that the Sharps lock is what is called a "back action" lock.
This means the mainspring is to the rear or back of the tumbler/hammer arrangement instead of being to the front as is most common. Those with the mainspring in front of the tumbler/hammer are known as "front action" locks.
There are some high quality Flint Locks that may also be "back action" in style and placement of internal parts.
My best,
Blair

[Johnson Barr]

I added a set screw (1-72 x .125 stainless steel) to the trigger on my .50-70 1863 New Model. The screw takes up the trigger/full cock sear slop. I now have adjusted the trigger let-off to a nice crisp 3 pounds. 

[Blair]

The set screw system does indeed work very well.
However, when tapping the hole drilled into the tumbler just behind the full cock notch, it can be very easy to snap or brake the threading tap off.
This can be a real heart breaker.
Annealing the area to be drilled and tapped is a must. Provisions for doing this are available and still keep the annealing in a very small area on the tumbler.
My best,
Blair

[Thomas (Tom) Horn aka James Hicks]

Update on weakening the trigger pull... Many thanks to all who responded.  I weakened the Main Spring (trigger portion of the spring). That did not work... Evidently I weakened it too much. When Installing the weakened spring with the vise lock, the portioned weakened bent under pressure and did not work. So, I did another spring... all I did to this spring was remove all the factory machine marks and HIGHLY POLISH the spring. I highly POLISHED that portion of the trigger blade that pushes up on the Sear which pushes up on the trigger spring. I then HIGHLY POLISHED that portion of the SEAR where the trigger spring rides. Using the Lock Vise installed this spring in the lock. White gun grease where the trigger spring rides on the Sear. And I polished the side of the sear that rides next to the Lock Plate. I also polished the notches for the half cock and the full cock.  By doing this the trigger pull is now at 3 lbs. I found this interesting....the Main Springs came from Taylor's and Co., so maybe when the spring are made they all have different trigger pulls... do not know.  I can live with the 3 lb pull, it is smooth and crisp, not heavy like the original spring.  Learning all this was at the cost of 2 spring, $40 bucks. No biggy.  But one thing I did learn... hour glassing is not the cure for lightening the '74 Sharps. But polishing the Spring and those parts where there is metal to metal contact (the flat area of the sear and the side that rides against the Lock and that blade top of the trigger that pushes the sear up when pulling the trigger) solved my heavy trigger pull.  This is not a task for the faint hearted. For those interested, not all Lock Vises are equal either. Track of the Wolf sells 2 types, a cheapy and an English Deluxe Vise. Do not waste your money on the cheapy... does not work well, the English Deluxe Vise works as it is suppose to.  This was an experience.... laughing.

[Gabriel Law]

I've come to this thread a little late.  I've had almost a lifetime's experience working with side locks in guns - mostly of the muzzle loading era.  Reworking springs can make an enormous difference in felt trigger pull.  Just today, I worked on an Indian made Long Land Pattern Brown Bess musket with lock issues.  The trigger pull was close to 11 pounds when I began, and when I was finished, it was a titch over 4 pounds.  All the difference in the world.
The purpose of the sear spring, in the case of Tom Horn's Sharps, the lower and thinned end of the mainspring, is simply to push the nose of the sear up into the tumbler's notches.  It is not designed to hold the sear in that position - that function comes from the angles cut on the sear's nose, and on the tumbler's full cock notch.  These angles are critical.  In addition, the amount of engagement of the sear in that full cock notch, ie:  how far the sear's nose has to travel before it parts company with the tumbler, is also very important.  That is where that set screw comes into play.  On really crudely made locks, I have simply soft soldered a shim of brass to the tumbler to fill the full cock notch, and then filed it away, a little at a time until the sear engaged safely, but released easily, producing a very crisp but light trigger pull.
But there is another issue with the Sharps.  And that is the way the trigger is hinged.  I suspect that in your rifle, Tom, the trigger is pinned through a boss in the trigger plate, and that very close to the plate itself.  The best mechanical advantage for a trigger is to have the trigger hinged very high - about level with the sear's pivot screw.  This could be accomplished by removing the boss from the trigger plate through which the trigger is pinned, and replacing it with a block of steel that allows the trigger to be hinged about level with the sear's pivot.  The higher you hinge the trigger, the more mechanical advantage it will have working against the sear's arm, rotating the sear's nose out of the tumbler's full cock notch.
But beware that if the tumbler does not have a fly or detent, lightening the trigger to make it easier to shoot accurately may cause the nose of the sear to engage the HALF COCK NOTCH as the tumbler rotates and the hammer falls.  A heavier pull will cause you to keep the trigger pulled, and the sear out of the way of the half cock notch.  All that disappears with a fly or detent in the tumbler.
I know this is too little too late, but i hope it will help you next time, or perhaps someone else experiencing these problems.

[cheatin charlie]

I was on the phone yesterday talking to Charlie Hahns to order some new tubes for my 1859 Sharps paper cutter.  If you don't know
Charlie belongs to the NSSA and has a business converting the breech block so they rifles do not jam up with fouling.  Anyway I asked
if he worked on locks to smooth and lighten the trigger pull.  He told me to try this trick to reduce trigger pull before I sent toe lock
to him because this might solve my problem.  I now have an imprint of my palm on my fore head from smacking myself as in why
didn't I think of that !
    He told me some mainsprings have a ramp that the screw bears against that you can adjust in or out to adjust spring pressure on
the sear.  If mine didn't try putting brass shim between screw and spring until I got the tension I wanted on the sear.  Bingo so simple
in 15 min. I had reduced the trigger pull to my liking. 
    Now no grinding on the spring !  So simple even a caveman like me could do it 

[Thomas (Tom) Horn aka James Hicks]

Response to Gabriel Law and Cheatin Charlie -

Gabriel I thank you for the information... never to late to learn things.

Cheatin Charlie- After I did what I said in the post on the "update".  As I reassembled the Lock and the Main Spring I too was asking myself... WHY IS THIS SCREW ON THE LOCK PLATE (Large screw that sits at the bottom portion of the Main Spring Trigger portion of Spring.)  .. this is a "TENSION SCREW". I tried turning the screw out some, but that did not work. I saw your post this morning and thought I would try what you said.  I tried different size shims and the third shimm accomplished what you stated CC.  I tested the trigger pull and it was down to 2.5 lbs of pull.  Well live and learn...

By polishing the Main Spring and getting rid of all the factory machine marks and polishing those areas I spoke of on the Sear and the trigger where metal to metal meet... and then shimming the underside of the trigger spring a wee bit... This has been one heck of a LEARNING EXPERIENCE. Thanks a bunch Cheatin Charlie... got the trigger pull to where I want it.

I thank all of you who posted your thoughts on this.  Wishing all of you a prosperous and healthy new year.  Happy trails to you.  Tom Horn

[LT Col Long]

Hi gents my problem is just the opposite of Thomas Horn's.  I too have a Armi-Sport Chiappa 45/70 cav carbine.  I finally fired the little critter this past Friday and (as it seems to this old Msgt) trigger pull is less than a pound!  I did one shot with a thin glove on and it fired way before I was ready.  I have not taken the gun down as of yet, but am I reading correctly that I should work in reverse of Thomas Horn's problem?  3 to 5 pound pull on a trigger is more liking to my fat fingers than a extremely "Hair Pull."

Maj SH Long

[wildman1]

Maj SHLong, you definitely should get that trigger pull fixed, one pound is way too light. wM1

[LT Col Long]

Maj SHLong, you definitely should get that trigger pull fixed, one pound is way too light. wM1

Roger That!  Starting this project today.

Maj SH Long