How to tune a Kibler (or any) lock for lighter trigger pull

[rich pierce]

For a first ever build, from a kit or whatever, I think you did a great job with a reasonable likeness to the Schreit rifle with your carving, etc!

And don't be put off by a couple of comments; Lot's of guys here build something, call it a such and such, when it has no likeness to the original such and such what so ever at all!

There's only so much you can do with a kit gun, and I think you did a fine job!
John

I agree you did a fine job adding decorative elements from the Schreit rifle, which also is the time period you’re going for. You’ve got skills. Hope to see more of your work.

[Jim Kibler]

As I opined in my first post I Think reducing the thickness of that sear spring might reduce the effort needed to pull the sear out of full cock & it seems others agree but what if you feel that the pull weight is actually a little too light? Would taking some off the tip of the sear spring so it bears further back slightly increase pull weight ?

If you want to increase pull, I would carefully back cut the full cock notch such that it traps the sear.  A very tiny amount is all that would be necessary.

[EC121]

Before you grind the spring, take the mainspring out and set the lock to full cock.  Then hold the lock nose down and slowly push the sear bar.  If the hammer moves back before the sear clears the notch, the notch or sear nose is off.  Making a hard trigger.  If it starts to move down before the the sear nose clears the notch, one of them is also off.  Making a possible unsafe trigger, because the lock might be using sear spring pressure to maintain the notch engagement. .

[Jim Kibler]

I will also note that we use a belt grinder with a contact wheel that fits the radius of the spring to thin it down, but you can file a spring down as well.  They are plenty soft to do this.  Follow up with some abrasive paper.

[Bob Roller]

Jim is correct, listen to him. If you’re asking how to do it, you do not need to attempt it. Let Jim do it for you. Not trying to belittle your skills, but it is very easy to make an unsafe lock that would be a danger to you and anyone around you.

Jim is also right about the two things that have the biggest impact on trigger pull is sear nose to sear notch engagement and the strength of the sear spring.

The sear notch needs only to be deep enough to hold the sear in place safely. The sear spring needs to be only strong enough to keep the main spring from overcoming its ability to hold the sear nose in the sear notch.

Both of these operations are tricky to obtain and be safe.

[Bob Roller]

I did not post  and no idea why my name appeared on this subject  but I agree with this instruction but would add the fit of the sear screw
should be a factor as well.
Bob Roller

[Greg Hartman]

If you want, send the lock to us and I’ll lighten the pull as light as it can be and still be safe.  No charge.

I do three things, carefully polish the tumbler notch and sear tip as well as decrease sear spring thickness slightly.

  Wow, talk about costumer satisfaction. Mr. Kibler is the best!]

That is true for sure.

[Greg Hartman]

For a first ever build, from a kit or whatever, I think you did a great job with a reasonable likeness to the Schreit rifle with your carving, etc!

And don't be put off by a couple of comments; Lot's of guys here build something, call it a such and such, when it has no likeness to the original such and such what so ever at all!

There's only so much you can do with a kit gun, and I think you did a fine job!
John

Thank you!

I agree you did a fine job adding decorative elements from the Schreit rifle, which also is the time period you’re going for. You’ve got skills. Hope to see more of your work.

[Greg Hartman]

I will also note that we use a belt grinder with a contact wheel that fits the radius of the spring to thin it down, but you can file a spring down as well.  They are plenty soft to do this.  Follow up with some abrasive paper.

Based on all of this info, Jim, I think I will give it a try myself (even though your offer to do it for me is more than kind and typical of my experience with your company).  As I understand it, all of your lock parts are interchangable, so if I mess this up, I can just buy new parts and start again - correct?  If I can do so safety, I'd rather DYI.

Here's the new Berks County Woodsrunner with a well-worn Dickert copy that was one of my first builds long ago:




Greg

[rich pierce]

Greg, glad you joined and are showing your work. Great to see what folks have been up to.

[Greg Hartman]

I wanted to report back because I appreciate those here who took their time to provide answers to my question.  Today being yet ANOTHER rainy day in Berks County PA, I decided to dig into this project.

While I really appreciate Jim Kibler's very kind offer to do this for me, I wanted to try it myself.  Knowing that I could buy interchangable replacement parts if I messed-up gave me confidence.  Bottom line - it was easy-peasy to do, didn't take much time; and I ended-up with a crisp, slightly sub-2 pound trigger pull with zero creep or overtravel.  Bashing things around a good bit to try jar the sear out of engagement with the cock at full bend, had no effect, so I feel the work did not compromise safely at all.

First, I carefully stoned the sear notch and the sear nose - not changing any angles, basically just mirror polishing with a very fine stone under magnification.

Then, I thinned the sear spring.  I didn't want to use even a small grinder, like a Dremel, for fear to going too far, too fast with that already rather thin metal; and/or introducing any heat and screwing-up the temper.  So, I just used a fine file and my engraving vise.  I went very carefully, frequently going through the tedious process of reassembling the lock to test the strength of the spring.  I filed the flat and a slight bevel on each side.



Eventually, I got it thin enough for the pull weight I wanted; then finished and polished the spring, so that hopefully no cracks could develop along the file stroke marks.  This is the best pic I could get of the completed file work to try to show the final thickness of the spring.  It's not a very good photo - sorry.



I didn't need to do anything to the mainspring.

All back together with a perfect rigger pull.   Thanks again to those who helped and to Jim Kibler.



Greg

[smylee grouch]

Thanks Greg for that photo rundown on your efforts. Nice looking gun BTW.

[Jim Kibler]

Greg,

Sounds like it worked out well.  Great job! 

All the best,
Jim

[Scota4570]

One safety thing, I require is that the sear returns to full depth of engagement, by itself,  if I pull it part way.   

[Greg Hartman]

Thanks Greg for that photo rundown on your efforts. Nice looking gun BTW.

Thank you!

[Greg Hartman]

Greg,

Sounds like it worked out well.  Great job! 

All the best,
Jim

Thanks; and thanks again for your kind offer.

[Greg Hartman]

One safety thing, I require is that the sear returns to full depth of engagement, by itself,  if I pull it part way.

Apologies for my ignorance, Scota, but I don't understand. 

Do you mean a situation where you start a trigger pull and then let off without "firing" the lock?

If so, that's not an issue here because there is zero slack, take-up or creep.  The trigger is like the proverbial breaking glass rod.  Either it's pulled or it isn't - no part way is possible.

Or do you mean trying to pull the trigger when the gun is at half-bend?

Once again, you can't move the trigger at all with the gun at half-bend - you have to pull the cock back a bit to disengage the sear nose (correct term?) from the sear notch, then pull the trigger before you can let the cock down from half-bend.

Thanks in advance for taking your time to explain.

Greg

[Scota4570]

It is impossible to have zero trigger movement. 

The sear nose must move in the notch, say 0.020".  The sear nose should be flat and 100% engagement in the notch.  The sear bar is about triple the distance from the pivot as the sear nose.  So that has to move about 0.060".  The trigger shoe is about 3X as far from the pivot as the place where it bear on the sear bar.  Add in about 10% for workign tolerances and you have the trigger shoe moving about 0.2".  This is expected. 

IF you pull the trigger 0.1" and move the sear nose half way across the full cock notch in the tumbler, does it return to the fully engaged position in the full cock notch if you release the pressure on the trigger?  If it does not you have a rifle that might fire by bumping it. 

It can be checked by working with the lock in the bench. 

I am glad you are happy with how it turned out.  I am not saying anything is wrong. 

[Jim Kibler]

I see no problem with the sear not returning to the bottom of the notch if the pull were stopped in mid-pull.  Also, I do not make flat sear noses.  At the very least they should have a radius that would match a circle drawn from the sear screw pivot.  More radius is sometimes better and not unsafe in the slightest.

[Scota4570]

Yes, A true radius is excellent.  That is commonly done on 1911s.  I have seen sear noses that were made into a point or had the inside cut away to reduce the depth of engagement in the tumbler notch.  Those are not a good way to do it, I should have been more specific.  I may be overly cautious.  I prefer to have the hammer of cock cam back a very tiny bit as the sear nose come across of the tumbler notch.  I also defer to the judgment and experience of Jim.  Bottom line is that making it safe, durable, and have a nice clean trigger pull is takes careful work. 

[bluenoser]

At the very least they should have a radius that would match a circle drawn from the sear screw pivot.  More radius is sometimes better and not unsafe in the slightest.

Thanks for that Jim.  That has long been my contention, which has generated some pretty heated campfire/shop discussions.  For clarification, are we correct in interpreting "more radius" as a shorter radius?

[Greg Hartman]

It is impossible to have zero trigger movement. 

First, thanks once again, Scota, for your time in responding.  You are right of course.  Apologies for not being more clear.  What I should have said is that there is no discernable trigger movement.  When the trigger moves, the lock "fires". So, it's impossible, for me anyway, to pull the trigger "just a little" to test whether it will return to battery.

The sear nose must move in the notch, say 0.020".  The sear nose should be flat and 100% engagement in the notch.  The sear bar is about triple the distance from the pivot as the sear nose.  So that has to move about 0.060".  The trigger shoe is about 3X as far from the pivot as the place where it bear on the sear bar.  Add in about 10% for workign tolerances and you have the trigger shoe moving about 0.2".  This is expected. 

IF you pull the trigger 0.1" and move the sear nose half way across the full cock notch in the tumbler, does it return to the fully engaged position in the full cock notch if you release the pressure on the trigger?  If it does not you have a rifle that might fire by bumping it. 

That all makes perfect sense.  I did bash the rifle around quite hard with my hand from different directions with the lock at full bend to simulate a fall or the like.  I wanted to see if I could somehow disengage the sear nose.  Nothing happened, no matter what I did, so I feel pretty secure.

It can be checked by working with the lock in the bench. 

  That I will try.

I am glad you are happy with how it turned out.  I am not saying anything is wrong.

Thanks!

Greg

[Greg Hartman]

I see no problem with the sear not returning to the bottom of the notch if the pull were stopped in mid-pull.  Also, I do not make flat sear noses.  At the very least they should have a radius that would match a circle drawn from the sear screw pivot.  More radius is sometimes better and not unsafe in the slightest.

I noticed that when I stoned the sear nose.

[Greg Hartman]

Yes, A true radius is excellent.  That is commonly done on 1911s.  I have seen sear noses that were made into a point or had the inside cut away to reduce the depth of engagement in the tumbler notch.  Those are not a good way to do it, I should have been more specific.  I may be overly cautious.  I prefer to have the hammer of cock cam back a very tiny bit as the sear nose come across of the tumbler notch.  I also defer to the judgment and experience of Jim.  Bottom line is that making it safe, durable, and have a nice clean trigger pull is takes careful work.

One of the cool things about this endeavor is that, no matter how much you know and how long you've been at it (it's been 50 years for me), there is always much more to know about both gunmaking and about their historical context.  There are always folks who know more than you do, and, often, they are willing to share that knowledge.

A couple of gratuitous pics of a fancy hunting Jäger I built a few years ago,







And a very plain military Jäger, intended to be an exact copy of the one my ancestor carried as a Hessian Jäger in the Battle of Saratoga in '77:





If you are still here, Jim Kibler, I'd be an anxious customer for a "kit" in Jäger style!!  After I'm done with my latest Kibler kit, of course.   

Greg

[Jim Kibler]

At the very least they should have a radius that would match a circle drawn from the sear screw pivot.  More radius is sometimes better and not unsafe in the slightest.

Thanks for that Jim.  That has long been my contention, which has generated some pretty heated campfire/shop discussions.  For clarification, are we correct in interpreting "more radius" as a shorter radius?

Yes, you understand what I’m trying to say about the radius.