TC percussion Lock, new fly, no workee

[PaulTBarton]

I replaced the fly with a NOS part. The old fly was too worn down to hold full-cock.

This new fly cannot hold full-cock either as the sear just slides down until it releases the hammer.

The fly face (the part that contacts the sear) is not at right angles to the hammer pivot, hence the sliding. The sear seems not broken or worn at the tip.

How much can I adjust that fly face to get this lock to function correctly?

Thanks,
IdeZilla
ala BartSr aka PaulTBarton
Mesa, AZ.

 

[bubba.50]

are you havin' trouble with the fly or the full-cock notch on the tumbler?

 

[Zonie]

Most of us refer to the surface the nose of the sear engages with as a notch.

In your case, we are speaking of the full cock notch in the tumbler. (The part that rotates inside the lock).

A "fly" is a very small piece of steel that can rotate back and forth. It is located right next to the half cock notch in the tumbler.
The fly's job is to keep the nose of the sear from entering the half cock notch after the sear has disengaged with the full cock notch.

Now, with that worked out, it sounds like the full cock notch in your locks tumbler is worn at an angle.
This would keep the nose of the sear from holding it in the full cock position.

The best solution is to try to get a new tumbler and install it in the lock.

If that is not possible, the only remaining solution is to grind the worn notch so that it once again is at a 90° to the axis of the tumbler.

To do either of these things, the hammer or cock must be removed from the square drive on the tumbler before the tumbler can be removed from the lockplate.

 

[Grenadier1758]

The fly will be no where near the sear when the lock is at full cock. The fly will lift the sear off the surface of the tumbler when the sear is released from full cock. The diagram may help some. The sear at full cock will be resting in a notch on the back of the tumbler past the fly. The diagram shows more of the lock in transition as the nose of sear approaches the fly and the half cock flat. You will need to replace the tumbler or the sear.

 

[PaulTBarton]

Well, those answers explain it all. I thought the fly held the lock at full, but you say no. OK, that (full-cock) I can fix now that I understand the fly workings. Half-cock does work fine. I will investigate the sear/tumbler "challenge".

Many thanks to those answers, I really appreciate them.

PaulTBarton
aka BartSr aka IdeZilla

 

[PaulTBarton]

The full-cock notch (shelf) is still in place and looks fine, no wear.

After looking at and working said lock, the coil spring (and it's guide rod) hits the mounting screw boss way before the full-cock notch arrives.

Hey, this thing used to work fine. :cursing:

Previous to replacing the old fly, I had removed the coil spring and guide rod (who knows why?). Now after re-assembling the coil spring and it's guide rod does this non-full-cock appear. Yes the nose of the guide rod is in place into the tumbler.

I will continue working on this lock until it works as designed.

Ugh,
PaulTBarton

 

[PaulTBarton]

OK, all is back together and working again.
The main spring diameter is bigger at one end. Swapped ends of that spring and it all works as new. This is probably not the real solution but for now it is OK. Full-cock is working, fly is again working, set triggers work as before.

Whew, and thanks again!
PaulTBarton

 

[Col. Batguano]

Once you pull these things apart and examine them, they are remarkably simple to understand aren't they?

 

[PaulTBarton]

Yes!
Now looking to convert to Flint.

PaulTBarton

 

[nwtradegun]

it would be far cheaper to buy a flint tc hawken. you will need a lock, new breech plug and costs if a gunsmith has to do it.