lock problem

[David R. Pennington]

Well, I have a Twigg lock that had a real wimpy mainspring. I made a new spring, better than the original but it wasn't quite stout enough either. I finally got around to making another spring. Forged out a heavier blank and made new spring. Fitted to lock, hardened and tempered and works really well. Good and stout. Cycled the lock out of the stock and it works great. Sparks like crazy. I fitted lock back in the mortise, had to trim out a couple spots. Can't see any binding in the mortise but the frizzen won't flip all the way open. I take the lock out and cycle it and the frizzen opens every time.  Well I quit on it for now. Any ideas?

[Virginiarifleman]

David, Check to see if the frizzen is touching the wood anywhere.sounds like its binding and when you relieve pressure it works.

[mountainman70]

How long you been a mechanic?I dunno,what time is it?How ye be,bro,missed ya  at last shoot.If you put the lock back in,and loosen a bit,you might find where it is bindin.Then git that big ol barlow out an whittle a chunk of'n the o-fenndin area.Hope ya got 'nuff wood to spare.I knows ye like them slim guns.hahahah,Dave F

[Acer Saccharum]

Is there a chance that the frizzen is flipping all the way open, then bouncing back, coming to rest against the flint?

You can put a little tell-tale ball of modeling clay or wax where the frizzen tail hits the spring. If ye ball is squished, then that's the problem.

[WadePatton]

Is there a chance that the frizzen is flipping all the way open, then bouncing back, coming to rest against the flint?

You can put a little tell-tale ball of modeling clay or wax where the frizzen tail hits the spring. If ye ball is squished, then that's the problem.

balls of clay!  (added to range gear)  Hadn't considered the rebound possibility, but has had some apparent failures to pop pan. 

Managing these rocklocks is no-snooze job! 

[Don Getz]

I know what you mean about the lock, kind of a mushy spring.   I have a neat english sporting rifle, 60 cal., with engraving
by John Schippers.   It just hangs on the wall now, but never did like that main spring.   Shortly after I built this rifle I ran into
Dave Ehrig at Dixon's, showed the gun to him, and talked him into taking it along to Canada to shoot a caribou, which he did
and he did an article on the hunt in Muzzle Blasts.   I'll bring it along to Dixon's........Don

[smart dog]

Hi Dave,
You did not mention any marks on the barrel so I assume the frizzen is not binding on the barrel.  Certainly, it could be bouncing back but I also wonder if the lockplate is warping slightly when you tighten down the lock screws.  The Twigg plate is long and narrow and might be easily distorted by the screw tension.

dave

[Pete G.]

I've got a lock that used to do that when the lock was cycled, but when actually firing it never did it. It used to worry the heck out of me quite a bit until I finally convinced myself that I didn't really have a problem. It has now apparently worn in enough to fix itself. Perhaps the push from the prime igniting was just enough to push it over.

[Bob Roller]

With the stock mechanism,the Twigg needs more help than a new mainspring.The cock and frizzen are big and the leverage of the feeble mainspring is no help.One the other hand,is it one that I made up using the Twigg externals.I hope not.Putting a bit of clay on the flint sounds OK for a test to see if a rebounding frizzen is the problem.They can bounce quickly and give the appearance of incomplete opening.

Bob Roller

[Acer Saccharum]

I had a lock that bounced the frizzen back so hard it self-knapped the flint...1/8" at a whack. I wouldn't have know if it weren't for all the flint flakes in the pan. 


We haven't heard from the original poster, and I'm curious if he discovered what the problem is.

[Mark Elliott]

The evidence of the problem is usually there right in front of you if you can see what you are looking at.   Unfortunately,   I have the problem of not seeing what is right in front of me for quite some time; a real problem when driving.

[David R. Pennington]

There is no binding on any wood. I smoked and checked everything when I reinstalled the lock. The frizzen clears the barrel ok. The lock plate is not warping. I tried it with the side nails loose and it still did it. I believe Acer hit it. I believe the frizzen is rebounding. That would explain why it doesn't do it when I cycle the lock  in my hand. I act as a shock absorber. When installed in the rifle it rebounds. I tried some really big musket flints and it doesn't rebound. It did knap a couple of the smaller flints I tried, so I believe rebounding is the problem. Now how to fix that?
Bob I wish it were one of your locks!
I wish this lock and I had never met.

[bob in the woods]

I had somewhat of a similar problem with an "Indian i.e. India " made lock. I was able to get it to work by judiciously altering the toe of the frizzen. It was a file and try thing. I cannot claim to know exactly what I was doing , but it seemed to make sense at the time. I moved the pivot point and angle of the toe slightly .

[smart dog]

Hi Dave,
Generally, rebound means the friction with the feather spring is too weak.  Either a stronger spring is needed or the contact with the frizzen toe must be firmer.

dave

[Dave B]

a simple way to test if a stronger spring on the frizzen would work is to put a wood shim in between the leaves of the feather spring. It will stiffen the resistance and decrease the likelihood of rebound. Increasing the hump height on the tip of the spring may help as well.

[Curtis]

DavidR, take note of the angle of the frizzen toe when it is completely open.  File a slight flat spot so it rests flat on the frizzen spring in the open position.  (you will have to remove the frizzen to file the flat)  This will act as a slight "catch" or "speed bump".  Also make certain your frizzen spring has good tension, which it sounds like it does if the frizzen doesn't rebound when the lock is handheld.

This has helped me before. ymmv.

Curtis

[LRB]

   Sometimes, removing a little metal on the underside of the tail will cure it. That allows the frizzen to go farther forward, and the toe cam farther rearward on the spring, adding a little more resistance to rebounding.

[Acer Saccharum]

I tried opening and re-shaping the frizzen spring, and changing the cam on the frizzen toe, with dismal results.  I finally 'fixed' my rebound problem by placing the flint bevel UP, which made the flint hit lower on the frizzen, which resulted in the frizzen not opening so hard.

To really fix the problem, I need to lighten up the mainspring. But I got sick of working on the durn thing.

[Bob Roller]

Inverting the flint solved the problem? Sounds good to me.No altering of springs or other parts because the fix was readily available.All of the flintlocks I send out have a flat side down flint installed and ready to go.A high striking flat side up flint will knock the frizzen open while the flat side down will give a better scrape across the face of the frizzen.

Bob Roller

[Acer Saccharum]

I went thru lots of changes until I found the bevel up solution. I even curved the frizzen face more, to get a more shearing stroke instead of impact. This didn't hurt a thing, but didn't fix the bouncing back.


Experiment with how far out the flint needs to be. A slight change in the flint can make a big difference where the sparks hit. Striking too high on the frizzen can cause most of your sparks to miss the pan. When you find a position that works, make note of distance from frizzen when on half cock and frizzen shut, and the bevel up or down. Record that info, and put it in the patchbox.

[David R. Pennington]

Well I fooled with the cursed lock some more this evening. It works ok with big musket flints. Rebounds with any smaller flints. The flints have to set out long in the jaws on this lock or the top jaw screw will strike the frizzen. I verified the rebounding with Acer's clay ball trick. (Thanks.) I haven't tried reshaping frizzen toe yet but when I put the wood wedge in to stiffen the frizzen spring tension that stopped the rebound. I'll pull the frizzen next and file a little before I make another spring.
I really hoped I could get this lock functioning reliably. I like the rest of the rifle. It shoulders great and points like my finger. I have never even gotten to shoot it enough to work out the right load and sight in because the lock was so frustrating. I don't like wall hangers. I want to build shooters.

[Acer Saccharum]

I heated my frizzen spring red, opened it up, then rehardened and tempered. It works fine with a LOT more pressure, but it didn't stop the rebounding, which surprised the heck out of me.

I think this comes around to the fact that the springs must balance each other. Mainspring strength should not overpower the frizzen spring (this is my problem). Nor should the main be so wimpy that the frizz doesn't flip the frizz open, or throw a decent spark.

Locks are tricky.

[Vomitus]

  The Chambers late Ketland is a good example of bevel up. Bevel down and she knaps 1/8th inch at a time.

[Old Bob]

Rick, on my old .40 I used a Bud Siler kit and most of the time I had to use flints bevel down. Once in a while I'd get one that struck too high, digging into the frizzen or cracking the flint. It depends on the height on the hump and angle of the bevel. I've been buying more flints with lower angles the last couple of years and using them bevel up resulting in better sparks. If they wear down to the point that the jaw screw begins to strike the frizzen, I can sometimes flip it over and get several more shots out of it.

I agree that a weak feather spring or worn frizzen can cause rebounding, but in my case I had a frizzen which was worn so thin you could just about shave with it. Still sparked great but the toe was worn and the pivot hole was wallered out pretty bad. But it never rebounded. But it was too loose to suit me and I put a new one on. The spring was a little worn too so I changed it out too.

[David R. Pennington]

I finally got off work before dark this evening and took my rifle with the cursed lock out to the range after I made the new mainspring. We are getting along better now. I put 3 shots in the same hole and 3 in the 10 ring on one target. I hit the gongs every shot offhand at 100 yards. I nailed all the woods walk targets but one.
The 44 inch .40 GM barrel likes 55 grains 3F. I started with 45 grains shooting 3 shot groups and increasing 5 grains at a time. When I got to 55 grains I noticed the sound of the report changed and she started to "crack". That is when my group tightened. With 60 grains the group starts to open.
It still needs a stouter frizzen spring but I think we can begin to develop a relationship now. The pea sized round balls shouldl slow down my lead consumption some what.