Lock trouble

[wpjson]

Not sure where this should go, so I'll start here. I have an old timer I am working over. I am inexperienced at this and have a problem. I do not think it is a major deal, but here goes. The lock does not set at half cock, only full cock and only then after the set trigger has been set. It is a back lock, I believe is the term. When it fires the hammer falls hard and fast. Thanks.

 

[coloradoclyde]

some possible causes.....
dirty,
broken sear
Sear screw is out of adjustment.

A picture of the mechanism might be helpful.

 

[Black Hand]

Stuck fly (if it has one)
Lock bolt too tight
Broken half-cock notch
No half-cock notch (I have a lock without a half-cock)

 

[shunka]

As Black Hand pointed out, a number of old locks were set up with set triggers and the half-cock removed. I too have an ol .40 half-stock target rifle with a Leman lock that had this done.

Seemed odd to me , but was not uncommon.

yhs
shunka

 

[dave_person]

Hi,
One of the trigger bars on the set trigger probably is too high and will not allow the lock to hold at full cock unless set. That may also explain why the half cock (if there is one) does not work either.

dave

 

[Grenadier1758]

The first step is to determine if this is a lock or a trigger issue.

Remove the lock to see if the lock will go to half cock and full cock. You can also look at the sear engagement and fly function. Then look at the notches in the tumbler. If the lock functions in going to half cock and full cock, the its time to look at the triggers.

Is the tip of the sear touching the wood at the bottom of the hole in the lock mortise for the sear?

If the triggers can be set and the lever function can be seen through the lock mortise, you may be tightening the trigger plate too tightly and pulling the levers too deep into the trigger mortise.

Look at the parts that move and determine that none of them are rubbing wood.

Most of the time the trigger plate is tightened so much that the trigger levers are raised or the lock is pulled in so deeep that the sear is dragging and preventing the gun from functioning properly.

 

[wpjson]

Will have time tomorrow to check it out. A really big thanks to you folks :hatsoff:

 

[Billnpatti]

A will fully agree with Grenadier1758. :metoo: I had the same, or quite similar, problem when installing a new L&R lock and a set of R.E.Davis triggers in a gun that I was building. It would not go into half cock and the set trigger did not work properly. I found that the sear bar was rubbing against the side of the lock mortise and the triggers were set too deeply and were rubbing against the sear bar and keeping the sear from dropping into the half cock notch and keeping the trigger from setting. I relieved the inside of the lock mortise to eliminate the rubbing of the sear bar and I shimmed up the trigger mortise to keep the trigger from rubbing against the sear bar. Later, I ground off some of the trigger to keep it from touching the sear bar. I removed only enough so that a playing card could be passed between the trigger bar and the sear bar when at full or half cock. You want only a slight relief there or your trigger will have too much take up. Of course, the idea of a playing card fitting between the trigger bar and the sear bar is just an idea since once you have the lock and the trigger in place, you can't get a card in to see if you have that amount of clearance. It is determined by feel of the trigger after it and the lock have been put back into the stock. Just keep feeling the trigger and grinding gently until you feel just a slight take up in the trigger at full cock. That tells you that it is not sitting against the sear bar.

 

[Pete G]

First you need to figure out if the trigger is a single lever or double lever. A lot of the old triggers were single lever, meaning that the only way to fire the lock is by set trigger only. If the rear trigger bar is bearing on the sear it will hold the sear clear of the tumbler, which means the trigger needs to be coked first, then the lock. Not really the way we like to do things now, but it was rather common back in the day.

If it is indeed a single lever trigger, which a lot were, you may not have a mechanical problem at all; it is working as designed.

 

[desi23]

I have an original half stock set up this way. The lock itself has no half cock notch on the tumbler just a smooth rounded surface. The trigger has to be set for the gun to fire, the front trigger arm cannot reach the sear lever, only the set trigger arm can.

I've heard this type setup was often used on target guns though mine is a light, small bore (38cal) set up more like a hunting gun.

 

[wpjson]

Without having the lock in front of me, that sounds exactly like what I am facing. What purpose is served? Old timers never did anything just to be contrary. Everything had a reason.

 

[desi23]

I really wish I knew. The only thing I can figure is that since you must use it by setting the trigger you always have the same, very light pull. No choice of trigger options. Maybe they felt it led to more consistent and accurate shooting. Also no need for a fly in the lock since no half cock notch to hang up on.

 

[Pete G]

Without having the lock in front of me, that sounds exactly like what I am facing. What purpose is served? Old timers never did anything just to be contrary. Everything had a reason.

I know a couple that do. :wink:

 

[Artificer]

I imagine the gun you are referring to is percussion, as I don't think I have ever seen or even heard of a flintlock that does not have a half cock notch?

The purpose of the half cock is two fold: 1. To prime the lock/gun with little or no chance of an unintentional firing during priming and 2. As a safety feature should the cock or hammer slip off the full cock notch unintentionally and hopefully to keep the gun from going off unintentionally.

There was at least one or more foreign percussion military arms used during the WBTS that did not have a half cock notch. However, the full cock notch was so deep that the trigger pull was WAY heavier than normal even for a military gun and as such was hard to "set off" even when a soldier was ordered to fire. Not having the half cock notch was seen as a way to make the locks cheaper in those guns. I imagine that was the purpose on the lock in your gun.

Personally, I would not want a lock without a half cock notch, even on a target gun with an extremely light trigger pull. One's hands or feet can still slip and possible cause a disastrous result, should the gun go off unintentionally.

Gus

 

[Zonie]

Not sure where this should go, so I'll start here. I have an old timer I am working over. I am inexperienced at this and have a problem. I do not think it is a major deal, but here goes. The lock does not set at half cock, only full cock and only then after the set trigger has been set. It is a back lock, I believe is the term. When it fires the hammer falls hard and fast. Thanks.

The first thing you should do is to remove the lock from the gun and examine it.

Look to see if there is a half cock notch. It is the hooked notch towards the left the drawing below.



The unhooked notch shown with the nose of the sear engaged with it in the sketch is the full cock notch.

(You may have to remove the bridle that covers the tumbler to see the half cock notch. If you do remove the bridle, watch out for a very small piece of metal that can move. It is the locks, fly and it is critical to the function of a lock that is used with set triggers.)

If no half cock notch exists then you know why it's not working. If it does exist, the next task is to find out why it isn't working on your lock.

That gets us to the set triggers.

There are basically two types.
The most common one is the Double Set Double Phase (or lever).

With the DSDP trigger, the front trigger can fire the gun without the rear trigger being set.

In the picture below, it is the one at the bottom.

Notice that it has a blade on the front trigger.



This blade moves upward when the front trigger is pulled.
As it moves upward, it pushes against the sear arm that is sticking out inwardly from the lock plate.
This releases the sear from the notch it is engaged with.

The rear trigger also has a blade attached to it. It is drawn like this blade is behind the front trigger blade.
This rear trigger blade is spring loaded upward so it is always up if the rear trigger is not "set".

You need to find out if your trigger is a DSDP style before we can go on.

The best way to do this is to remove the trigger assembly but on some guns that means removing a pinned trigger guard. Pinned trigger guards can be a chore to remove.
If your trigger guard is just screwed on, remove it and then remove the trigger assembly.

If your trigger guard is pinned in place, another way to determine if the trigger is a DSDP style is, with the lock removed look down the hole in the stock where the sear arm usually is. (A flashlight helps to see down in the hole.)

Pull the front trigger to the rear.

If you see a metal blade rise up in the sear arm hole, your trigger is a DSDP style.

With these DSDP triggers, both the front trigger blade and the rear trigger blade should rest below the locks sear arm even if the triggers are not "set". Although the unset rear trigger blade is held up by the spring pressure, it should not be so far "up" that it touches the sear arm.

Because neither of the blades are touching the sear arm, the sear can engage the half cock notch or the full cock notch with the triggers left in a unset condition.

The answer to your problem is, the DSDP trigger is installed to deeply into the wood.
That places it so high that the rear triggers spring loaded blade is pushing against the sear arm if it is left unset.
That's why you need to set the rear trigger before you can cock the gun.

You can fix this by installing a shim between the trigger assembly and the stock or, by filing the top of the rear trigger blade down so it isn't pushing on the sear arm when the rear trigger is left unset.

The trigger assembly in the drawing above showing the Double Set Single Phase (lever) trigger shows that the front trigger does not have a blade on it. Only the rear trigger has the blade that will hit the sear arm.

For this reason, the front trigger cannot fire the gun unless the rear trigger is first set.

The blade or lever on these DSSP triggers always is high enough to push against the sear arm if they are not "set".

In order to cock a gun with a DSSP trigger, the shooter MUST first set the rear trigger.

That's just the way it is and the shooter must learn to get used to it.

By the way, a gun with a DSDP trigger MUST have a lock that has a fly in the tumbler.
If the lock does not have a fly to prevent the sear nose from entering the half cock notch as the hammer is falling, the half cock notch will prevent the hammer from falling all the way down to fire the gun.

With a DSSP trigger, no fly is needed in the locks tumbler.
With the spring loaded lever pushing up on the sear arm as the hammer falls, the sear cannot engage the half cock notch.

Let us know what kind of trigger you have and if there is a half cock notch in the tumbler.

 

[wpjson]

I went out to my cabin last Wednesday. Got back from hunting a bit early so I fired off a few rounds from my New Army Remington. Went inside at built a fire and started to feel a bit ill. Within a hour or so, I knew I was in trouble and headed out to the ER. Drove 50 miles to the ER. Had emergency surgery at 2am. damn near died.They had to remove a chunk of my guts. I am out of the hospital now, but still have to get back to the cabin for my guns. I will retrieve the rifle hopefully this week and will work on it all winter. Thank you so much for all the dope. Give me a week or so and I will be back in touch.