Getting Locks Tuned

Dropping off M Avance and Dave Gross Flintlocks at T Briggs house today. I want a light trigger pull on each. I find it improves my wife's and my flintlock shooting. Both rifles are real sweethearts! The Gross gun(wifes) had a bad spot in the bore when I bought it. I had Bobby Hoyt bore it to .50 cal and he did a great job. The Northeastern is in July so we must be ready!
Nit Wit

There’s not much more important than a well tuned lock. I was at a match on Saturday where a young shooter had a musket that would throw weak to no sparks. He had a lot of patience. More than I would have.

For trigger pull, sometimes I find it’s the lock and sometimes the setup of tge simple trigger. Often a combination and tuning the lock helps lighten it and makes it feel smoother.

I have a POS .45 cal flintlock I bought on a whim, Italian-made, "DART" brand.(?) Really should have kept my money in my pocket, but.....

Worst part is the mainspring - it takes less than four pounds pull to bring it to full cock. Sparks OK but not enough force to completely open the frizzen, therefore it might set off the prime, but most often not.

Any suggestions for a 'smith in Minnesota who might replace the mainspring for me?

I’d send the lock out. Making a new mainspring from scratch is a chore and takes me a couple hours to make, fit, harden, and temper.

I would compare the size and length of the mainspring to those of other locks in the Track of the Wolf catalogue. Their pictures are correctly sized. Find a mainspring that is dentical in length. Then fit that to the lockplate, re-locating the pin hole in the lockplate as needed. Faster and less expensive fix.

I was at a match on Saturday where a young shooter had a musket that would throw weak to no sparks. He had a lot of patience. More than I would have.

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That sounds like a frizzen-hardness problem, or a weak strike. I wonder what brand it was?

LD

Worst part is the mainspring - it takes less than four pounds pull to bring it to full cock. Sparks OK but not enough force to completely open the frizzen, therefore it might set off the prime, but most often not.

Any suggestions for a 'smith in Minnesota who might replace the mainspring for me?

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I just corrected that problem last night, on a CVA plains rifle. In my case the frizzen cam was too long, and it also needed polishing as well as the top surface of the frizzen spring.

In your case, since it's a POS anyway, you might try a DIY application. Any blacksmith can harden the spring for you, just have the smith heat it to cherry red, and then quench in 120 degree Canola Oil. After that it will be brittle. So you need to temper it.

For a knife I know folks that put the steel in an "oven", heating to 400-500 degrees, then air cool, and they do it twice, but that will probably still leave you a brittle spring. I was shown that a gun spring can be tempered by submerging in melted lead, which begins melts at 625° but for running ball it is closer to 700°.

So in the demonstration that I saw, the fellow attached a piece of copper wire to the spring so he could retrieve the spring, and then submerged the spring into the melted lead. He let it sit for about 10 minutes, and when he removed it, the lead didn't cling to the spring..., he removed it, then grabbed the end that was for the screw (this spring was held in place by a screw) with a pair of pliers, and tapped the pliers against the lead pot to get the lead to shake free. Then he let it air cool.

It seemed to have worked, as it didn't snap when he tried it in a lock. NO IDEA if this guy was "lucky" or if he had come up with a way for person without much tech to temper a gun spring.... but since you need to replace the part anyway, maybe you want to give it a try?

LD

High carbon steel like 1095 makes an excellent spring if it is first hardened and then tempered at 700°F to 900°F.

The 700°-750°F temperature of lead at a casting temperature is right in that zone.

People will see tempering temperatures lower than this if the 1095 steel is being used for knife blades and similar cutting tools because the 700°F tempering temperature reduces the steel hardness to something in the neighborhood of HRc 49.

Carbon steel at HRc 49 would quickly dull if it was being used as a knife but that hardness is great for a spring which needs to bend without breaking.

Loyalist Dave said:

I was at a match on Saturday where a young shooter had a musket that would throw weak to no sparks. He had a lot of patience. More than I would have.

Click to expand...

That sounds like a frizzen-hardness problem, or a weak strike. I wonder what brand it was?

LD

Click to expand...

Looked like a repro Bess from India. The lock was slow and sometimes did not throw the frizzen open. It looked like a combination of a weak mainspring and possibly a soft frizzen. The shooter’s dad was there testifying it had always been reliable before. That might be evidence of a thinly case-hardened frizzen.

Back to the current lock which is the subject of this thread: heating and spreading, then re-hardening and tempering the current mainspring can make it more powerful but puts an awful strain on it with high pre-load. Better is a new spring with beefier arms.

Hi,
1075 steel makes much more forgiving springs than 1095. After hardening as others describe a temper at 750 degrees for 1 hour will produce a reliable spring. Folks use lead pots and it works OK but I use a programmable heat treating oven that allows me to get the conditions exactly right for the steel and hardness required.

dave

Folks use lead pots and it works OK but I use a programmable heat treating oven that allows me to get the conditions exactly right for the steel and hardness required.

Click to expand...

Well..., if you want to do it in a correct manner, I'm sure that's the way to go.... :grin:

The fellow that was doing it with the lead had come up with that method to explain how it might have been done with the lower tech of the 18th century..., since he'd at that time not found any manuals telling him how to do it. He'd seen a demonstration of a fellow who did it by burning an amount of petroleum oil and another substance under a quenched spring, and he thought "well they didn't have that flammable stuff back in 1770" so was looking for something they did have to get up around a good temp. He was probably below the temp he should've been at. Of course that was 20 + years ago, and folks have probably uncovered sources that are more accessible today...

LD

Dead on Dave, with all you recommended there. Tempering a spring below 725° is inviting trouble, and 750°F. is a proven ideal temp for springs that will last. Just to add, many believe the strength and flex of a spring can be regulated by temper heat. It cannot. Strength and flex is controlled by the thickness of the steel.

One of the things often left out of helping spring longevity is the profile shape of the main spring arm and edge corners.One wants the bend back to be completely free of bend nicks and cracks , especially on the outside corners and then both the width and thickness taper to be evenly and gradually reduced for the best balance of tension and effective response.
What this does is even out the flex over the greatest area distributing the movement and lessening metal fatigue.
Two springs made of the same material quality and identically and properly heat treated can show a marked difference in longevity if there are stress points caused from improper limb and edge profiling. Same thing is true of an archery bow.
In my opinion these two areas are just as important to spring function and life as is the exact heat treat protocol.
Actually I have two programmable heat treat ovens used regularly but for small springs use the old black smith method of drawing temper consisting of mixing equal parts of kerosene and clean motor oil, (the first ones probably used sperm oil which used to be common)covering the part on it's side in a shallow dish or can and lighting with a propane torch. Let it burn out usually taking about a half hour and the spring will be perfectly tempered every time. I have never had it fail in many years of use. I have no idea of the heat generated over the half hour but the old dead guys knew a thing or two about spring heat treating as well and many of their springs are still going a century or more later.

Another issue in lock tuning of interest to me is frizzen rebound. All frizzens rebound to some degree as they cam over from heel(closed position) to toe (open position) and bounce off the frizzen spring but they should not be able to get back to the flint with the hammer down.
This movement can be altered by both the shape of the spring and positioning of the toe on the frizzen.
I did quite a bit of experimentation on a lock that came to me as screwed up as possibly could be. Almost every thing was out of balance from the hammer swing radius, main spring tension, frizzsen hardness, spring shape and tension.
I first sent the gun back as it was brand new to the maker but it came back just as useless as it left. I finally decided I could make every part needed if necessary so tore into the project with nothing more in mind than to solve the issues and learn from the experience. Every thing mentioned was experiment on and altered until it worked satisfactory.
The frizzen was hardened which generated good sparks and the newly made spring was given a small bend rise between the frizzen heel and toe at the closed position. That very slight rise was just enough to keep the frizzen from rebounding back to closed and breaking flints.
This might be something folks want to try when tuning frizzen rebound.

Hi Rich, who would you send a lock to for tuning? I've seen Brad Emig's name bandied about however I went to Cabin Creek's web page and could find nothing about them taking in repairs (but they make some beautiful things!). I've got an L&R lock and that just won't spark.

Contact L&R. That would he the best place to send an L&R lock to have it refurbished. I sent an older L&R lock (Late English) back and it was refurbished with updated internal parts and then sent off to Mike Lea for adding the flash guard.

I have had Brad Emig tune several locks for me and would not hesitate to send him another. L&R's become very reliable after he is done.
:thumbsup:
Dave

Thanks for the replies, gentlemen. As it is a new lock, I suppose I should reach out to L&R first.

By-the-by, last weekend I had the opportunity to look over a Bob Roller-modified lock. Bob's other avocation must be building watches and clocks! Beautiful work he does.

Hope it works out. Even Bob Roller’s locks use L&R externals including the frizzen most of the time, so geometry is very good or he would not mess with it.

I have an L&R Durs Egg I tuned and my shooting club members comment on how fast it is. When all is right it seems like a percussion gun to the ear.

One more edit. I recently half-soled a frizzen on a custom lock that was a poor sparker. I was just tired of trying to get to harden correctly. I don’t think there was enoug carbon in the frizzen to really spark hot. So I ground it back and put on a piece of handsaw blade. I fitted it, hardened it, and soft soldered it with low temp solderthen quenched immediately. Voila! Many hot sparks. I would not do this as first or second choice on a mass produced lock with parts available.