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

[Greg Hartman]

I recently completed my first ever kit build.  I used a Kibler Woodsrunner as a base to make a circa 1761 Berks County, PA longriifle in the style of Johannes Schreit.  Gotta say that I was really pleased with the quality of the parts; and the fact that I could finish, carve and engrave my own unique creation without the usual hundreds of hours doing boring, tedious work like inletting a swamped bbl.






















I'm happy with the completed rifle in terms of both appearance and accuracy (once I got a load worked up for it).  The trigger pull is fine for a hunting rifle - crisp, with no creep or overtravel. BUT, the trigger pull is pretty heavy for target shooting.  I have heard that there are some "tricks" for tuning a Kibler round-face lock to reduce trigger pull weight. 

Could the assembled experts here share any of those methods with me?

Obviously, I don't want to do anything that would compromise safety or reliability.

Thank you in advacne for your time!

Greg Hartman

[Stoner creek]

Buckridge Flintlocks makes a single set trigger that will work. It’s designed after the Cain trigger. This is going to require some extra work because your gun is finished. I’ve installed one on a finished gun so I know that it can be done. Done correctly you can cycle the lock into half and full cock without first setting the trigger. Expect a full day to do this. Prepare yourself for a tad bit of frustration.
W

[rich pierce]

Not specific in any way for a Kibler lock; this is for any lock.

A simple trigger is hard to get to below 3 pounds and give a crisp let off. Approaches to get a lighter pull fall into 3 buckets for me: polish, lube, and if all else fails, go to geometry class. I seldom gain much by polishing exceot a possible increase in smoothness of pull.

I check that nothing is binding by removing the mainspring only, being well familiar with that, and move the tumbler and sear through their range of motion. This is just checking to I haven’t over-tightened the sear screw and pinched the sear so it doesn’t move freely. Tumbler and sear should move effortlessly without hanging up at all.

To polish, I get magnification, a vise, and my “go slow, be meticulous, and use your skills” part of my brain engaged. Polish the top surface of the sear where the sear spring rubs on it. Polish the bit of the sear spring that rides on top of the sear. 600 grit is nice enough for me. I get rid of any grit in bolt holes or anywhere on the parts and oil before reassembly.

Under magnification with the sear nose contact area (where it engages the tumbler notch face) set level in the vise, I sometimes very lightly polish the miniscule contact edge with diamond hones. If the angle gets messed up at all or rounded or shortened, things are way worse off than before starting the “improvement project.”  I occasionally do the same with the full cock notch only if I see roughness and  can see where I’m removing tiny imperfections and can polish flat.

My next check is to see the trigger moves freely through the range of motion enough to go beyond lifting the sear the minimum amount. Also to check that the sear can move very freely without hanging up with the lock installed in the stock.

Now I check how the pull feels. If too heavy for my preferences I move the pivot point of the simple trigger closer to the sear pivot.  This increases leverage, reduces trigger pull, and reduces crispness. A 0.150” adjustment may allow enough metal between the 2 pin holes to drill a new hole through wood and the trigger to install a pin and not collapse the existing hole.  Maybe 0.180” movement rearward is the upper limit for me. Again I emphasize none of these procedures I follow have anything to do with the locks or kits of any maker - because I have no experience building or assembling kits from anyone over the past 40 years.

[Greg Hartman]

Thanks very muhc for the response!  I've built longrifles and Jägers with set triggers; and they have their place for sure, but a set trigger wouldn't be at all "correct" for this rifle.  I'm really just asking if there is something that can (safely!) be done with the Kibler lock itself to reduce the pressure needed on the sear bar.

Greg

[Greg Hartman]

Thank you, Rich.  As I do with every lock when building, I stripped the lock down and made sure everything fit well and nothing was binding.  As noted above, I was very pleased with the quality of the Kibler parts and didn't see any need to do any polishing like on this rather poorly made lock for another recent build (a Blunderbuss):





I will look more closely to see if anything could be improved by polishing, but I doubt that will make much difference given the very high quality of the lock out right out of the box.

Given that this rifle is not primarily a target rifle (it's a .54), I'm more than a bit reluctant to trade a very nice crisp, if slightly heavy, pull for a longer, creepy pull.  Also, frankly not too excited about trying to restructure the simple trigger.

I guess I was hoping that there might be some magic cure particular to the Kibler lock itself - a place to put a set-screw or something.  I wouldn't be surprised to learn that doesn't exist.  I really appreciate you taking your time to provide such good suggestions.

Greg

[Scota4570]

Kibler locks are excellent as made.  These locks are made by CNC to incredibly tight tolerances.  Of the dozen or so I have worked with, I never found anything that needs fixing.  Do not mess with the sear tumbler of sear spring.    You will not find any roughness or binding.  Everything is optimal as made.



Locating the trigger pivot to give more mechanical advantage will lower the pull but increase the travel and vice versa. 

[Greg Hartman]

Thanks, Scota - pretty much what I figgered.

[Greg Hartman]

Stoner Creek - With respect, it's not an exact copy and wasn't intended to be, but, to my eye, it certainly is in the style of this Schreit rifle in terms of overall architecture, carving and engraving.










Greg

[smylee grouch]

Just curious if JUST EVER SO SLIGHTLY reducing the thickness of the sear spring would make the trigger pull weight less. Not so much that it wont snap the sear into full cock but slightly reduce the poundage effort to pull it out of full cock.

[JTR]

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

[Jim Kibler]

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.

[Zarkoon]

How do you polish a hardened lock part ? What about the inside face of the sear that pivots to plate? Why not polish that ?

[rich pierce]

How do you polish a hardened lock part ? What about the inside face of the sear that pivots to plate? Why not polish that ?

Stones and diamond laps or stones polish hardened parts without rounding things over much. But of course sanding belts, belts on grinders also polish hardened steel readily.

The sear should not be binding. The only reasons I know of for significant resistance of a sear to rotation outside the stock is its being squeezed by the bridle or the screw is not perpendicular and it’s canted. Polishing the sear foot sides is good but not going to impact trigger pull. Some have a ring that’s supposed to act as a bearing. Hard to polish those. I’ve lapped sears, tumblers in tumbler holes, sear screw axles, frizzen screw axles before. In bad cases using valve grinding compound. Blow it all out with brake cleaner spray.

[EC121]

I have done what Jim says.  I stood a rifle on a bathroom scale with the hammer down.  Then I pushed the trigger.  There was about 3lbs. of sear spring pressure to overcome.  After grinding the sear spring I took 2lbs. off the pressure needed to just move the trigger, and at full cock trigger pull was still crisp and much lighter.  And safe.  Before I started I also took the precaution of ordering a spare spring.  Just in case.    

[Daryl]

My "match" rifle is .69 calibre, just saying. It also has a simple trigger, good 3 pounds + a tiny bit more.
Back when I shot 3 position, our triggers HAD to lift a 3 pound weight to qualify. I think people today are spoilt!!!
Just my opinion, of course.

[Martin S.]

I have done what Jim says.  I stood a rifle on a bathroom scale with the hammer down.  Then I pushed the trigger.  There was about 3lbs. of sear spring pressure to overcome.  After grinding the sear spring I took 2lbs. off the pressure needed to just move the trigger, and at full cock trigger pull was still crisp and much lighter.  And safe.  Before I started I also took the precaution of ordering a spare spring.  Just in case.   

Can you explain the procedure for "grinding the sear spring".

What do you grind it with?

Are you just making it thinner?

Do you grind the entire spring, or just the lower half that contacts the sear.

I'm not sure I'll ever try this, but I would be interested to know how it is done, just in case I need to do it someday.

Thanks!

[FlinterNick]

When I assemble locks I usually polish parts before i harden them, i mostly just use hand tools, fine files, small cuts of paper, stones etc. I do my best to smooth out the contact area’s, remove burrs etc. I use a barrel tumbler with steel shot to burnish the parts, then i harden and temper last. If there’s a modification that needs to be made I normalize the part and start over.  For tunes a lot of times just dropping the part in a barrel tumbler with steel shot and some burnishing compound does the trick. I try not to reduce the thickness of springs if i don’t have to. I think Kilber’s springs are fine the way they are. I’ve had a few here all i had to do was take a small deburring tool and work the edges, i shot peened the parts on a high setting and the locks were much smoother and lighter.

[EC121]

I have done what Jim says.  I stood a rifle on a bathroom scale with the hammer down.  Then I pushed the trigger.  There was about 3lbs. of sear spring pressure to overcome.  After grinding the sear spring I took 2lbs. off the pressure needed to just move the trigger, and at full cock trigger pull was still crisp and much lighter.  And safe.  Before I started I also took the precaution of ordering a spare spring.  Just in case.   

Can you explain the procedure for "grinding the sear spring".

What do you grind it with?

Are you just making it thinner?

Do you grind the entire spring, or just the lower half that contacts the sear.

I'm not sure I'll ever try this, but I would be interested to know how it is done, just in case I need to do it someday.

Thanks!

I just used a Dremel to grind the lower arm both ways until it felt right. 

[bama]

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.

[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.  It was my first build from a kit, but I've been building flinters (about half and half longrifles and Jägers, with a few fusils) on and off for almost 50 years, John.  I really liked the Kibler kit because I could get to what is the fun stuff for me (finishing, carving and engraving) very quickly and without a lot of tedious boring scut work.  The quality was amazing.  I had the rifle rough assembled in a day.  The Woodsrunner kit was perfect for this project because (despite Tallbear's nasty crack, which I will ignore, this being my first - and very likely last - use of this site) the stock architecture with its "Roman Nose" comb and wrist extending down into the butt a bit is classic Berks County.  Yes, Schreit built straight comb stocks - looking more Lancaster than Berks, but Haga and other Berks makers used the "Roman Nose" comb.  As noted above, this wasn't a copy but rather a gun built in the "style of".  Much (but not all) of the carving and the engraving are inspired by Schreit - the stock architecture more by Haga.  I am Berks County born and bred and my first language was PA Dutch growing up, so like to think I have some understand of the history of the area and its rifles.

I am not, however, familiar with the Kibler lock, this being my first kit build. Thus, the original question.  I'm not a "social media" person and was just hoping for some expert advice.  I guess I wasn't expecting snarky comments.

Greg

[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.

Thank you, Jim.  I will take you up on that. 

As noted this was my first ever "kit" build and I was amazed at the high quality of the parts.  I bought my second kit from you a few weeks ago.  It's very nice to be able to quicky get to the parts of building I most enjoy.

Greg

[Greg Hartman]

My "match" rifle is .69 calibre, just saying. It also has a simple trigger, good 3 pounds + a tiny bit more.
Back when I shot 3 position, our triggers HAD to lift a 3 pound weight to qualify. I think people today are spoilt!!!
Just my opinion, of course.

Nothing wrong with a big caliber target gun, Daryl.  They can be very accurate.  I have a couple of .62 Jägers that really shoot.  It's just that you go through a LOT of lead and powder.  I prefer a .45 for pure target shooting, FWIW.

Greg

[Greg Hartman]

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.

Thanks, Bama.  I wouldn't hesitate to try it with any of the crappy old locks I have, but the precision Kibler lock is new to me.  Since Jim is kind enough to offer to tune it for me, I'm more than happy to turn it over to his skills with my appreciation.

Honestly, the trigger pull isn't all that heavy - and its perfectly fine for a hunting rifle, maybe even more desirable than a light pull fr that purpose.  I'm just used to lighter pulls on my other single trigger flinters.

Greg

[flintlock hunter]

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!]

[smylee grouch]

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 ?