GPR Set Trigger Problem

I have a Lyman .54 GPR. First I pull the set trigger. Then, when I squeeze the front trigger, the set trigger "pops", and the gun does not discharge. Then I repeat the process, but this time the gun discharges. Any ideas about what is wrong and how to correct it? Thanks.

I am most definitely not an expert by any means on the workings of guns, but I had a similar issue with my .50 GPR. WHen I pulled the lock out to have a look I couldnt find anything. Put it back in and it worked every time since. Only thing I can figure is that when it was built some small part of the stock was interfering with the workings of the lock.

Hopefully someone will be able to give you a better answer than that though.

Whenever I have seen this problem, it's usually a loose screw holding down the set trigger spring, which causes the spring to act "weak". The first time the trigger blade smacks the sear bar, it moves it a little, but not enough to trip the sear. The second time, the sear is closer to tripping, so the weak smack will trip it. Remove the triggers and check for a loose screw.

If that doesn't work, take rigwelder's suggestion and look for something interfering with the lock action. Also look for something interfering with the set trigger blade.

I'll betcha it's a loose screw though :grin: . Good luck. Bill

Hawken-Hunter said:

...when I squeeze the front trigger, the set trigger "pops", and the gun does not discharge. Then I repeat the process, but this time the gun discharges.

Click to expand...

I'll bet you're using the factory nipple and CCI caps. Been there, done that, got the t-shirt. Switch to Remington or RWS caps if you can get either, and the problem is gone. If those caps aren't readily available in your area, change the nipple to an ABL- Anything But Lyman. :grin: It's virtually a standard issue with new Lymans.

I've had good luck using CCI caps with hot shot nipples, but have less tendency for spent caps to stick in the hammer when using Ampro brass nipples from Track of the Wolf.

If you're not using the Lyman/CCI combo, I'd still bet that a nipple/cap incompatibility of some sort is at work, and changing one or the other will fix it.

I think there is some confusion here. What do you mean by "pop"? Do you press the set trigger and hear a "pop" but the hammer doesn't fall? Or, does the hammer fall but doesn't cause the cap to explode?

The way I read it, he's describing the "click" that the rear 'trigger' makes when it's released.

Course I've been wrong before.

If it is the "click" and the hammer is not releasing when the rear trigger releases it is probably due to the blade on the rear trigger interfering with some wood.

With the lock removed, pushing forward on the rear 'set trigger' should raise a metal blade up so it is easily visible in the hole in the wooden stock that clears the locks sear arm. If it doesn't raise freely, removing the trigger and then finding out where the wood is interfering will show what needs to be removed.

While the lock is out of the gun, also check the movement of the sear arm. It is the metal thing that's sticking out away from the lock plate and fits into the hole I mentioned above.

Some people think all of the screws inside the lock should be really tight.
This is not true. The one that holds the sear in place below the bridle should be "snug", not tight and the arm should move freely.
A little oil on all the moving parts will also help the lock to operate as it should.

If we are talking about the hammer actually hitting the cap on the nipple but the cap is not firing it is probably because the nipple is too large or it is deformed from dry firing.

Remove the lock and look for crud or interference. Them make sure that the screws that hold the trigger in place are tight. I believe this requires removing the trigger guard.
Geo. T.

:hmm: With all due respect, I have to ask if the set trigger is the same as that on my much older GPR where the set trigger has 2 distinct clicks before it fulfills its function. Make sure you pull the set trigger all the way back before pulling the front.

i bought a new gpr .54. very few shots thru it and the hammer and triggers were acting up. I tore it apart and found a bent bridle and a fly without a support leg (?). I polished all the parts replaced the fly and hammered out the bridle. it now works fine, but that gun was brand new and im am NOT impressed with the newer production guns. irishtoo

My original description was not very accurate. By "pop", I meant the rear trigger pops/clicks when I squeeze the front trigger; the hammer does NOT fall.

check the fly

Looks like I'm going to have to learn about the inner workings of the lock. I've never even heard the terms bridle and fly when talking about guns. Thanks for all the suggestions.

Follow this link to see a post with pictures that define the various lock parts.

If your computer savy you might even want to do a "screen grab" so you will end up with a photo you can store in your computer.
http://www.muzzleloadingforum.com/fusionbb/showtopic.php?tid/254598/

These locks are fairly simple and if you bare with me I'll try to explain how they work.

There is the mainspring that provides the power to move the hammer.
Most locks use a flat spring for this but the TC and Lyman locks use a coil spring. Either way, the mainspring pushes on something called a tumbler.

The tumbler rotates and because the hammer is attached to it on the outside of the lock, as it turns, the hammer moves.

The tumbler on your gun has two notches cut into the round part of it that is inside the lockplate.

Often there is a 'bridge' that is held against the inner surface of the lockplate with a hollowed out area that covers much of the tumbler.
This gives support to the tumbler to help it withstand the heavy spring pressure produced by the mainspring.
This 'bridge' is called the "bridle".

There is a lever with a small nose on it called the sear. The nose of the sear engage these notches in the tumbler. The sear has a light weight spring that pushes its nose against the body of the tumbler.

The notches are the half cock notch and the full cock notch.
The half cock notch is a hooked affair that traps the nose of the sear to keep it from accidentally disengaging.

The full cock notch is just a small shelf that the nose of the sear engages to hold the tumbler and hammer in the full cocked position.

A slight movement of the sear will slide its nose off of this full cock notch allowing the tumbler to turn and the hammer to fall.

The sear has a arm or projection that sticks out away from the inner surface of the lockplate.

When the trigger blade pushes up on this arm the sear is moved to release the tumbler.

Your gun has a "set trigger" which has two blades that can hit the sear arm.
The front triggers blade simply moves upward with you pull the front trigger.

The rear triggers blade normally doesn't touch the sear arm unless the trigger is "set" and released.

Setting the rear trigger cocks it by compressing a heavy spring. Once it has moved to the "set" position a small latch on the front trigger engages it to hold it there.

A very light movement of the front trigger will release this latch.
When it does, the heavy "set trigger" spring drives the set trigger forward rapidly.

As the set trigger moves forward, the blade on top of it rapidly moves towards the sear arm.

Its high speed gives it the momentum needed to hit the sear arm causing it to release from the full cock notch in the tumbler. The hammer starts to fall.

Because the momentum of the rear set trigger is now absorbed by the sear arm, it bounces away from the sear arm and returns to its unset position.

Meanwhile, the tumbler is moving and the hammer is falling and the sear spring has pushed the nose of the sear back against the outside of the tumbler.
As it turns, the half cock notch is rapidly approaching the nose of the sear.

Without something to prevent it, the nose of the sear will go back into the half cock notch stopping the hammer fall and possibly breaking the sears nose or the half cock notch.

To prevent this from happening a very small movable part is installed in the tumbler at the half cock notch. It's one and only job is to keep the nose of the sear from entering the half cock notch when the tumbler is moving from the full cock position.

This small part is called the "fly".

The fly is easy to move and it is usually held in place in the tumbler by the bridle.

GEtting back to your guns problem, for some reason, the blade on the rear set trigger is not hitting the sear arm or it is not hitting the sear arm hard enough to cause the nose of the sear from moving out of the full cock notch.

Find out why this is happening and it will be easy to fix.

Zonie said:

Find out why this is happening and it will be easy to fix.

Click to expand...

My Hatfield would not reliably fire, just like the OPs. After checking out everything I could think of, without correcting the problem, I finally noticed when taking the lock bolt in and out the lock plate would slightly rock back & forth. Found out someone had bent the lock bolt, which moved the sear arm up by just enough to keep the trigger bar from engaging the sear reliably. Straightened the bolt problem resolved.

The set trigger on the Lyman guns also has a screw behind the rear trigger that adjusts the strength of the "set triggers" spring.

The Lyman set trigger is rather hard to pull to the "set" position and some owners adjust that screw to make setting it easier.

In doing this, they can reduce the spring pressure so much that although the trigger is easy to "set", it doesn't have enough "poop" to cause the rear triggers blade to reliably trip the sear out of the full cock notch.

Sometimes, increasing the spring tension will solve the problem.

Wow! Thanks for all the detailed information. I'll check out the link, study-up, and then take a look inside the lock. Thanks so much!