Mark IV doesn't always fire

Stefan A

Stefan A

Member
Joined
Oct 21, 2020
Messages
531
Location
Southern York County, Pa.
I think it's a trigger bar issue, but I have no idea what to do about it. Too much to explain, so I made a video. Basically, I installed the Tandemkross Victory trigger, and then the problem started happening. The trigger bar seems to move out of position after firing once. It then has to be reset by pulling out the trigger pin just a bit. You'll see. Thanks for any suggestions.

 
Right at the start of the video it showed the trigger not resetting, going forward.. I have a MKIII so it may be a little difference. The plunger spring that is in the trigger moves the bar up. I would tear it back down and make sure the new trigger is not binding. These bars from the factory has burrs and not always straight and may need some straightening. Also check for burs and binding in the plunger hole. Then add just the bar to make sure it's putting upper movement on the bar, freely, not binding. Now another possiable problem is that you have the springs in the right position, flipped.
 
gwpercle said:
Hmm...hmmm... Let's See ... I have an idea ... lets uninstall the Tandermkross Victory Trigger and go back to basics ... Ruger Trigger that works !
Gary
Click to expand...
Well, I might put it back to see what happens. But there’s got to be a solution for this. Certainly the company doesn’t stay in business by making stuff that doesn’t work…
 
Stefan A said:
trigger bar
Click to expand...
Is the disconector. The bolt coming back pushes it down, out of contact with the sear. It need to move up & down freely, as you know.
Something is binding with that black thing on the right. Measure the diameter of old trigger vs new? Screenshot_20240224-214805_Chrome.jpg
 
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The trigger bar/disconector is pushed up by this spring. Screenshot_20240224-214805_Chrome.jpg

When you pull out the trigger pin, does the trigger move forward more, when it resets. There maybe a forward trigger stop on the trigger? The Marks 1 factory trigger has one, on target models.

Both over travel & reset travel were on a Mark 1 factory target trigger.
 
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243winxb said:
The trigger bar/disconector is pushed up by this spring. View attachment 1196329

When you pull out the trigger pin, does the trigger move forward more, when it resets. There maybe a forward trigger stop on the trigger? The Marks 1 factory trigger has one, on target models.

Both over travel & reset travel were on a Mark 1 factory target trigger.
Click to expand...
That little wire spring against the right side did fall out during the process. I think that’s what you’re pointing to. I managed to get it back in and it looks right. Maybe not. Not sure how else to place it. Worth looking over.
 
Trigger return spring sounds like it is weak. When I installed the Tandemkross trigger in my Black Mamba I had the same issue. Replaced that small spring and the problem went away.

Good luck with it.

You may also check and see if the trigger is rubbing. The early models did. There should still be a video on how to check and repair this.

Steven
 
AzShooter1 said:
Trigger return spring sounds like it is weak. When I installed the Tandemkross trigger in my Black Mamba I had the same issue. Replaced that small spring and the problem went away.

Good luck with it.

You may also check and see if the trigger is rubbing. The early models did. There should still be a video on how to check and repair this.

Steven
Click to expand...
I went ahead and ordered another spring and detent. Although it seems to me the trigger is returning just fine. It's this trigger bar that moving unexpectantly. But I'll try anything at this point.

Spent another 45 minutes just now taking it apart and making sure everything was just right. I just can't fix this.
 
Apparently you did not check to see if the plunger in the new trigger is sticking like I posted in #2. I've had to deburr and enlargen the hole for the little plunger does not stick. Easy to test. Remove every thing except the trigger, plunger & spring and disconnector (trigger bar). Now the bar should be pointing up and way from it's normal position. Now push down on the bar to put it in it's normal position, and cycle it. Play close attention to the bar and the side of the receiver. The bar should not rub the receiver, if it is check for burrs and straightness. These are eay to bend and knock out of alignement if you not careful. If good. Add the hammer/sear/spring back into position making sure you get the spring orientation right. Test again.

Did you check to see if the new trigger is binding on the pin? All it takes is a small burr to cause problems. Did you oil the pin when you assembled the trigger spring. The pin can only go in 1 way if backwars the pin will not be secured and can backout.

My guess is there is a burr where the plunger goes into the trigger. and it's binding. Use just the plunger no spring and see if the plunger will fall out on it's own if inverted.

Measure the thickness of the new trigger and compare it to the original. If larger you may have to thin.

When I'm doing a MK.IIII trigger work the first thing I do is deburr and polish all the edges from the stamped parts.
 
Blue68f100 said:
Apparently you did not check to see if the plunger in the new trigger is sticking like I posted in #2. I've had to deburr and enlargen the hole for the little plunger does not stick. Easy to test. Remove every thing except the trigger, plunger & spring and disconnector (trigger bar). Now the bar should be pointing up and way from it's normal position. Now push down on the bar to put it in it's normal position, and cycle it. Play close attention to the bar and the side of the receiver. The bar should not rub the receiver, if it is check for burrs and straightness. These are eay to bend and knock out of alignement if you not careful. If good. Add the hammer/sear/spring back into position making sure you get the spring orientation right. Test again.

Did you check to see if the new trigger is binding on the pin? All it takes is a small burr to cause problems. Did you oil the pin when you assembled the trigger spring. The pin can only go in 1 way if backwars the pin will not be secured and can backout.

My guess is there is a burr where the plunger goes into the trigger. and it's binding. Use just the plunger no spring and see if the plunger will fall out on it's own if inverted.

Measure the thickness of the new trigger and compare it to the original. If larger you may have to thin.

When I'm doing a MK.IIII trigger work the first thing I do is deburr and polish all the edges from the stamped parts.
Click to expand...
Sorry, I just haven’t been able to get to everything yet. I’ll let you know when I check these things. So I understand, are you saying I need to also remove the hammer so I can get the trigger bar to be more free? Sorry, I’m just not understanding what you want me to do there. BTW, the spring and plunger is original to the gun. The TK is designed to use Rugers. The pin is part of the thumb ledge and it is not possiblle to put it in any other way. It seems that the plunger/spring are pretty free. When you push it down it come right up. Makes solid contact with the trigger bar.
 
Stefan A said:
Sorry, I just haven’t been able to get to everything yet. I’ll let you know when I check these things. So I understand, are you saying I need to also remove the hammer so I can get the trigger bar to be more free? Sorry, I’m just not understanding what you want me to do there. BTW, the spring and plunger is original to the gun. The TK is designed to use Rugers. The pin is part of the thumb ledge and it is not possiblle to put it in any other way. It seems that the plunger/spring are pretty free. When you push it down it come right up. Makes solid contact with the trigger bar.
Click to expand...
For testing purposes yes. Then you add the parts back and continue testing. Once it starts hanging again you will know which area to concentrate in. With all the other parts removed it's easier to detect if the bar is straight and not being binded up when installed. It should be parallel to the side. Most I see are anything but straight.

I keep referent to the plunger/spring because I've seen this in so many that I work on with aftermarket parts. The Disconnector bar is another high problem area. If it has a twist or not straight they bind. Deburr all the edges on the bar it will make things more reliable.

You may want to paint the frame with a marker or smoke to see where the bar is rubbing on the reciever. I've even polished that part of the receiver in the past to reduce friction.
 
Stefan A said:
The pin is part of the thumb ledge
Click to expand...
In video, when thumb ledge is moved out, the trigger bar popped up.
Is the trigger bar a factory part or custom add on?

This is where i would look? The MK1s do not have it. Just a pin & clip to hold trigger pin in place.

The MKIV Factory spring looks like it holds the Factory trigger pin in place? No clip like MK1?

Great video.
 
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Update:

I installed the original trigger and everything works perfectly. In the video, you see me push down the trigger bar/disconnect which makes it fail. You cannot pull it back up. You have to pull the pin out just a bit, as I demonstrated, to get the bar to pop back up and work again. With the factory trigger, that trigger bar moves up and down very easily. When you press down on it, it does not stick as in my video. It springs right back up due to the plunger/spring in the trigger. The plunger and spring work perfectly in either trigger - no binding or anything like that. the trigger bar will not pop back up even when I pull up with great force. So, the plunger and spring is not the issue. The 2 triggers are exactly the same width. So, there is something about the TK trigger that is making that trigger bar bind.

Blue - although I have yet to take the whole gun apart, I am sure that the area of concentration has to be the trigger bar. But as I said, it works fine with the Ruger trigger. So, I guess really, the trigger is to blame. It's causing the trigger bar not to work.
243 - it is the original trigger bar. The Pin, which is part of the thumb ledge, does not have an indentation to cradle the spring. I suppose that I could try the original pin with the new trigger.
 
The trigger bar needs the trigger to return fully forward. This resets the sear engaugement.

When it fails to reset, try moving the trigger forward, towards muzzle. A complete reset.
 
Solution:

Welp - I am a bit embarrassed by this, but I guess I have to explain myself... 243 - your last post made me consider this. The issue turns out to be the pre-travel set screw. You mentioned it earlier, and then in post 11 I confidently claimed the screws were set correctly. Well, the pre travel screw was in too far. I backed it all of the way out and the trigger bar, and everything worked as expected. So, I just finished re-adjusting the screw and found the sweet spot.

In my defense, in the TK video that I watched about installing the trigger, he said to generally set the screw so the trigger looks perpendicular to the slide. Which I did. But I guess I over estimated. Furthermore, he did say that if the trigger has a delayed reset, to back off on the pre-travel screw. But he didn't say anything about completely failing to reset.

Anyway, problem is solved and I appreciate all of your help. It made me dig deep and trouble shoot this thing. I learned a lot about the internals of this gun in the process - having also changed out the hammer, sear, and the thing that disables the mag disconnect.

Now, I just need to wait for my safety spring which went flying during the install to be delivered...
 
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