New to me Pedersoli 1805 Flintlock Pistol Catches on the Half Cock

[Putterboy2]

Hello,
I bought a Navy Arms/Pedersoli 1805 Harpers Ferry pistol at auction. Seems pretty sound, but I noticed that in dry fire, when I pull the trigger from full cock, the cock momentarily catches halfway through its release as it travels to the frizzen. If doesn't arrest there, but it feels like it skips over the catch at half cock. If I put rearward resistance on the cock to slow it in its travel, it will stop at the half cock position. If I don't, it will complete its travel but it bumps over the half cock catch on the way to the frizzen, so the travel is rough. I haven't fired it yet, still disassembling and cleaning. Has anyone else encountered this, and is it a simple fix, i.e. changing a spring, tumbler, etc.? Thank you for any thoughts.

 

[Zonie]

It sounds like the lock has a "fly" in it.

The fly is a very small little thing that is located at the half cock notch. It's job is to move to the rear and expose the half cock notch as the hammer is cocked so that allowing the hammer to move forward slightly, the nose of the sear can enter the notch.
When the hammer is cocked further towards full cock, the nose of the sear jumps over the fly and then enters the full cock notch, ready for firing.

When the trigger is pulled and the nose of the sear clears the full cock notch the hammer starts to fall.
If the nose of the sear is pressing on the outside of the tumbler, when it gets to the fly, the fly is pushed forward, covering, or blocking off the half cock notch.
This keeps the sear from trying to enter the half cock notch. At this moment, the nose of the sear rides on the fly, climbing over it and allowing the hammer to continue to fall.

In other words, what your seeing is totally normal if a fly is in the lock.
The thing to keep in mind is that the fly will only let the sear enter the half cock notch when the hammer is being lifted from the fired position. It will block off the half cock notch when the hammer is falling from any position above the half cock notch.

If you have the gun fully cocked and you want to put it at half cock, the only safe way to do this is to put your thumb on the hammer, slowly pull the trigger and let the hammer fall down to a position that is below the half cock. Then, you can raise the hammer slightly until you hear the sear enter the half cock notch. When you hear this, you can gently lower the hammer to the half cock position.

I'm mentioning all of this not only to tell you what is going on but to warn other people about the effects of the fly. Many people do not know about this and more than a few of them have tried to lower the hammer from full cock, directly to half cock. If they do this slowly they will find, like you have found, that sometimes the sear hangs up on the fly. It seems like the hammer stopped at half cock but in reality it didn't. It stopped on the fly.
If left in this condition, the slightest knock or jar of the gun can cause the sear to jump over the fly and allow the hammer to fall.
This can cause the gun to fire, possibly killing someone.

For guns with set triggers, a fly is needed to prevent the sear from entering the half cock notch.
Many of the guns made by the big factories in Italy have set triggers so it is not uncommon for the locks on all of their guns including the guns that have a single, simple trigger to have a fly in them.

 

[wiksmo]

Helpful to read the "warning" attached to the fly function. Just looked at the percussion lock schematic for my Italian-made Trapper pistol, and it does picture the fly. Does the warning apply to a percussion pistol similarly as to the Pedersoli 1805 flintlock pistol? Next time I remove the lock will be checking more closely the functioning of these parts. The parts and how they work together are still pretty new to me. TIA.

 

[Zonie]

I haven't bought a BP pistol for a long time so I was just going by what Putterboy2 said in his original post when I blamed the fly as the cause of the problem.
That said, I can't say whether the Pederesoli 1805 pistol has a fly in the lock or not. The way his pistol was acting is exactly what I would expect to see if its lock has a fly in it.

I would not expect to see a fly in a Military gun though.

 

[Grenadier1758]

The information / warning about the fly applies to any lock with a fly whether it is flint or percussion.

 

[wiksmo]

The information / warning about the fly applies to any lock with a fly whether it is flint or percussion.

 

[hawkeye2]

The lock does have a fly which was quite a supprise. If I pull the trigger slowly like I might do sometimes when dry firing I can feel the sear hit the tumbler at the half cock position. Pulling the trigger normally, if there is a normal pull with a 10 (more?) pound trigger, the sear clears the notch without issue.

The problem is really simple; the fly is way too long and it pushes the nose of the sear down as it passes over it which is what is felt at the trigger. I wish that were the only problem with the Harpers ferry lock but it has a lot of issues. If you find the lock impossible to remove after taking the screws out, put it on half cock. On mine the stop for the tumbler/cock allows the mainspring to travel below the plate when in the fired position hitting the stock hard enough that the lock cannot be removed.

Correction: I'm so used to the cock having a ledge that stops on the top of the plate that I just wrote as it did. The cock does not have a ledge and has no contact with the plate. The stop is internal.

 

[Putterboy2]

Thank you, Zonie, and the others who kindly replied. Reading between the lines, my understanding is that this is an as-designed function, and does not require anything to be done because this is not a malfunction. It's a quirk of the mechanism, and if it goes bang, it's working. If I'm mistaken about that, I'm open to any more wisdom from the community. Thanks again for your knowledge and expertise.

 

[Stantheman86]

My Tryon rifle and Pedersoli Hawken do this , if you keep your thumb on the hammer and ride it forward, you can feel the "hitch". If you just fire it, the hammer drops.

A cause that makes this worse is over tightened lock screws.

 

[Zonie]

The lock does have a fly which was quite a supprise. If I pull the trigger slowly like I might do sometimes when dry firing I can feel the sear hit the tumbler at the half cock position. Pulling the trigger normally, if there is a normal pull with a 10 (more?) pound trigger, the sear clears the notch without issue.

The problem is really simple; the fly is way too long and it pushes the nose of the sear down as it passes over it which is what is felt at the trigger. I wish that were the only problem with the Harpers ferry lock but it has a lot of issues. If you find the lock impossible to remove after taking the screws out, put it on half cock. On mine the stop for the tumbler/cock allows the mainspring to travel below the plate when in the fired position hitting the stock hard enough that the lock cannot be removed.

Correction: I'm so used to the cock having a ledge that stops on the top of the plate that I just wrote as it did. The cock does not have a ledge and has no contact with the plate. The stop is internal.

I've seen a number of locks that allow the tip of the mainspring to end up below the outside form of the lockplate when the lock is in the fired position. As you say, if one tries to remove one of these locks with the cock or hammer in the fired position, the tip of the spring will hang up on the lock mortise.
Usually, the owner will have the cock or hammer at half cock before they try to remove the lock. If they do this, they will never realize that the mainspring tip will hang up on the wood.
IMO, it's always a good idea to place the cock or hammer at half cock when removing or installing a lock into the stock.
(Never put the cock or hammer at full cock when you try to remove the lock from the gun. If it is at full cock and the arm on the sear bumps the stock while the lock is being removed, the cock or hammer will fall to the fired position and the power of it can easily crush or break a finger if it is in the way.)