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I dont know about interchange, but my Trade Rifle lock fires really well. I cant figure out why I cant go from full cock to half cock without opening the pan and going all the way down and back up.....:dunno:. Makes no sense! My Traditions lock does it flawlessly.
 
I dont know about interchange, but my Trade Rifle lock fires really well. I cant figure out why I cant go from full cock to half cock without opening the pan and going all the way down and back up.....:dunno:. Makes no sense! My Traditions lock does it flawlessly.
That's because the lock is working like it should. There is a fly in the lock to keep it from engaging halfcock and damaging it when you fire the lock. All locks that have set triggers should have this, and it is a sign of a better lock.
 
That's because the lock is working like it should. There is a fly in the lock to keep it from engaging halfcock and damaging it when you fire the lock. All locks that have set triggers should have this, and it is a sign of a better lock.
That is generally true. I have 4 rifles with set triggers that do not have a fly in the lock. The triggers have to be set before the gun can be brought to full cock.
 
I have one older (percussion) rifle that has a set trigger. There is no half cock notch in the lock, but the triggers are set up so that the triggers must be set before the lock can be brought to full cock as a "safety" measure. Here along the western bank of the Mississippi River, rifles built for the Over-the-Log, Table Shoots or Chunk Gun Shoots did not have half cock notches. Those rifles were built specifically for the target competition and not used for hunting. They were only brought to full cock when in position on the rest and the percussion cap was ready to be placed on the nipple.

The fly in the tumbler is a design feature to prevent the sear from entering the half cock notch as the hammer is driven forward by the full force of the mainspring.
That is generally true. I have 4 rifles with set triggers that do not have a fly in the lock. The triggers have to be set before the gun can be brought to full cock.
That sort of implies that there may be an interference, perhaps intended by the builder, between the trigger lever and the sear to limit the rifle to use of the set trigger only. But I would want such a rifle to have a fly in the tumbler.
 
I have one older (percussion) rifle that has a set trigger. There is no half cock notch in the lock, but the triggers are set up so that the triggers must be set before the lock can be brought to full cock as a "safety" measure. Here along the western bank of the Mississippi River, rifles built for the Over-the-Log, Table Shoots or Chunk Gun Shoots did not have half cock notches. Those rifles were built specifically for the target competition and not used for hunting. They were only brought to full cock when in position on the rest and the percussion cap was ready to be placed on the nipple.

The fly in the tumbler is a design feature to prevent the sear from entering the half cock notch as the hammer is driven forward by the full force of the mainspring.

That sort of implies that there may be an interference, perhaps intended by the builder, between the trigger lever and the sear to limit the rifle to use of the set trigger only. But I would want such a rifle to have a fly in the tumbler.
These are single phase set triggers, not like the more common double phase set triggers like on T/C guns and others.
 
I dont know about interchange, but my Trade Rifle lock fires really well. I cant figure out why I cant go from full cock to half cock without opening the pan and going all the way down and back up.....:dunno:. Makes no sense! My Traditions lock does it flawlessly.
I would be careful with that Traditions gun.
Often, a lock with a fly in it can give a false impression of being at half cock when in fact, the locks sear is just hanging up on the fly.

Others have explained how these locks with fly's in them work but I'll give my version of it.

First, with set triggers, the way they work is to have usually the rear trigger spring loaded. This rear trigger has a blade on the top of it and when the rear trigger is released, the spring drives the trigger forward which raises the blade upward. The blade whacks the sear arm causing the sear to release the fully cocked lock.
With a Double Phase set trigger, as soon as the blade has released the sear, it instantly moves away from the sear arm allowing the sear spring to push the nose of the sear back against the outside of the tumbler. The tumbler is now rotating due to the force from the mainspring.
With the nose of the sear against the outside of the rotating tumbler the half cock notch is rapidly approaching the nose of the sear.
If there is no fly in the lock, the nose of the sear will enter the half cock notch and everything comes to a stop. (This can break the sear and or the tumbler).

If there is a fly in the lock, the fly blocks off the half cock notch as the hammer falls so the nose of the sear hits the fly, jumps over it and again, comes down against the outside of the tumbler. With nothing in the way for the sear to hit, the tumbler and hammer continue down and the gun fires.

When the hammer or cock is raised from the fired position, the sear is pushing against the outside of the tumbler. When it reaches the half cock notch, it pushes the fly towards the full cock notch which exposes the half cock notch. If the shooter stops here and lowers the hammer, the nose of the sear enters the half cock notch and the gun is relatively safe.

Now, getting back to the Traditions.
The fly is designed to block off the half cock notch when the hammer or cock is rapidly falling. When the hammer or cock is slowly lowered from the full cock position, the nose of the sear can hang up on the fly rather than jumping over it.
If the sear does hang up on the fly, the tumbler will stop rotating so the hammer or cock will quit falling. This gives the impression that the lock is safely at half cock.
The problem is, because the sear is just hung up on the fly, a sharp blow, or even a mild whack to the gun can cause the sear to lose it's grip on the fly and jump over it as the hammer or cock falls to the fired position. Needless to say, this can cause a loaded gun to fire.

The moral of the story is: If you are raising the hammer or cock from the fired position and you want to set the lock to half cock, raise the hammer or cock until you hear the click of the sear falling into the half cock notch. Then, lower the hammer or cock to engage the half cock notch.
Do NOT raise the hammer or cock much past this 'half cock click". If you do raise it far enough for the sear to pass the fly and then lower it, you are right back in the "lowered it from a full cock" situation and the sear can hang up on the fly.
If the gun is at full cock and you want to set it to half cock, lower the hammer or cock down to the "almost fired" position below the half cock notch and then raise it back up until you hear the half cock "click".
 

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