SR9 Trigger Connector/Trigger Weight Questions

[mattbren]

I've read and followed Josh's excellent tutorial on tear down and polishing of the trigger assembly and it has resulted in a much smoother trigger pull. Like many of you, I have also anxiously anticipated the release of the Ghost trigger connector with the promise of a much lighter trigger pull. However, while waiting and waiting, I've been thinking a lot about how a simple trigger connector is going to give us the reduced trigger weight we all so desperately want, and I just don't get it.

I hope someone will correct me if I'm wrong, but the way I see it, the trigger connector (trigger bar reset) serves two basic functions. The first is to deflect the trigger bar downward at the end of the trigger stroke to disengage the sear from the striker tab. The second is to get out of the way to allow the trigger bar to reset. The first function is controlled by the angled tab and changing that angle will simply change the length of the trigger stroke before the sear disengages. The second function is a timing function controlled by the upper tab and the cam in the slide, so changing that would only change the trigger reset.

I'm happy with the length of the trigger pull and the trigger reset, all I want is a lighter trigger.

So it seems to me that the only two things that directly affect the weight of the trigger pull are the striker spring and the trigger bar spring (and some friction which the polishing helped reduce). I've read other posts about cutting the striker spring which I'm sure would reduce the trigger pull, but I'm not going to do that because I want my gun to go bang every time I pull the trigger. So that leaves the trigger bar spring. It's only purposes in life that I can determine are to counter the weight of the striker spring, and to continue pulling the trigger bar rearward after the sear releases.

All this considered, can we get the lower trigger weight we want simply by increasing the weight of the trigger bar spring and providing a greater offset to the striker spring? If so, does anyone know what the weight of the stock trigger bar spring is? Would there be any detrimental affects to doing this?

 

[3leggeddog]

I've read and followed Josh's excellent tutorial on tear down and polishing of the trigger assembly and it has resulted in a much smoother trigger pull. Like many of you, I have also anxiously anticipated the release of the Ghost trigger connector with the promise of a much lighter trigger pull. However, while waiting and waiting, I've been thinking a lot about how a simple trigger connector is going to give us the reduced trigger weight we all so desperately want, and I just don't get it.

I hope someone will correct me if I'm wrong, but the way I see it, the trigger connector (trigger bar reset) serves two basic functions. The first is to deflect the trigger bar downward at the end of the trigger stroke to disengage the sear from the striker tab. The second is to get out of the way to allow the trigger bar to reset. The first function is controlled by the angled tab and changing that angle will simply change the length of the trigger stroke before the sear disengages. The second function is a timing function controlled by the upper tab and the cam in the slide, so changing that would only change the trigger reset.

I'm happy with the length of the trigger pull and the trigger reset, all I want is a lighter trigger.

So it seems to me that the only two things that directly affect the weight of the trigger pull are the striker spring and the trigger bar spring (and some friction which the polishing helped reduce). I've read other posts about cutting the striker spring which I'm sure would reduce the trigger pull, but I'm not going to do that because I want my gun to go bang every time I pull the trigger. So that leaves the trigger bar spring. It's only purposes in life that I can determine are to counter the weight of the striker spring, and to continue pulling the trigger bar rearward after the sear releases.

All this considered, can we get the lower trigger weight we want simply by increasing the weight of the trigger bar spring and providing a greater offset to the striker spring? If so, does anyone know what the weight of the stock trigger bar spring is? Would there be any detrimental affects to doing this?

??????? no answers ???

 

[mattbren]

I went ahead and ordered a spring with what I believe will be a higher rate based on the wire diameter. It should arrive today, so I'll install it as soon as possible and post results. My plan is to test dry firing empty, then with snap caps, then with single rounds progressing slowly to double rounds. I can't see any reason why increasing this spring rate could cause the gun to go full auto, but I'm not taking any chances.

 

[jhearne]

Sorry I saw this early one morning while checking a few things on my iTouch and never got the chance to reply later that day....

I haven't put the thought into how that spring really effects the trigger pull, and I am interested to see what you find. You know the chance for a full auto pull is there, and I can see where it's a possibility if it keeps the gun from resetting properly.

Sorry I don't have any answers for you, I'm not great on springs and the like. Keep us up to date with what you find, be careful when you start going live.

Josh

 

[mattbren]

Reset occurs because the cam inside the slide pushes the trigger connector out of the way on it's way forward. This allows the trigger bar lift spring to push the trigger bar back up so that the sear is caught by the striker tab on it's way forward which pushes the whole trigger bar forward and resets the trigger.

It appears that the trigger bar spring pulls straight backwards or even up slightly so the amount of force needed from the trigger bar lift spring to raise the trigger bar back into position should not be affected. This is different than a Glock which uses the same spring to both pull the trigger bar rearward and upward.

Like I said, if this works at all, there will be a lot of one round firings before I progress to two round firings.

 

[jhearne]

Reset occurs because the cam inside the slide pushes the trigger connector out of the way on it's way forward. This allows the trigger bar lift spring to push the trigger bar back up so that the sear is caught by the striker tab on it's way forward which pushes the whole trigger bar forward and resets the trigger.

It appears that the trigger bar spring pulls straight backwards or even up slightly so the amount of force needed from the trigger bar lift spring to raise the trigger bar back into position should not be affected. This is different than a Glock which uses the same spring to both pull the trigger bar rearward and upward.

Like I said, if this works at all, there will be a lot of one round firings before I progress to two round firings.

Thanks for the info, will look into when I can and see what I can think of, got a good bit on my mind ATM so no guarantees.

Josh

 

[mattbren]

Josh,

I understand about you having a lot on your mind right now. I just read about your medical issue in another thread. I hope everything turns out well for you.

 

[jhearne]

Thanks man, got a few plans for some SR9 stuff once I'm well again.

Josh

 

[mattbren]

The new spring arrived today and it is much stiffer than the stock spring. Overall length and diameter of the spring are very similar to the original but it is made from 0.029" wire instead of 0.025" wire like the original.

Installation was very straight forward with the only issue being that I could not remove the roll pin that holds the spring in the fire control housing. It just wouldn't budge and I was afraid I was going to bend my pin punch. Fortunately, the spring has an open loop end on it so I was able to pry it past the pin. The new spring had closed loop ends so I clipped them with wire cutters to make them open loops.

One of my biggest concerns is what would happen if the new spring failed completely (broke). So after removing the original spring, I reassembled the gun without a trigger bar spring to make sure that everything would still work safely. Without the trigger bar spring, the trigger still resets due to the lift spring. The only detrimental affect of not having a trigger bar spring in the gun is that the trigger pull becomes very heavy because you are pulling directly against the force of the striker spring with no assistance.

Upon installation of the new spring, it was immediately apparent that there was a great deal more force pulling back on the trigger bar. After assembling the gun it was time to dry fire.

The trigger weight is now VERY light. I dry fired it at least a hundred times tonight and cycled the slide as fast as possible by hand between trigger pulls. There were no malfunctions of any kind and the trigger pull was amazing. In fact, it may be too light, or more accurately, lighter than the gun design can handle.

Trigger weight is determined by a balance between the striker spring force and the trigger bar spring force. With the new spring installed, these two forces are close enough to each other that you can start to pull on the trigger, and if you stop before it breaks, it and the striker stay where they are instead of returning forward. I don't remember the trigger acting this way with the original spring, but then again, I may have just not noticed. If someone could try that and let me know, I'd appreciate it. It does return forward if you push the safety back up.

Unfortunately, I don't have a trigger pull gauge, so I don't have actual numbers to give you. I plan to go to the range this Saturday to do some live firing and I'll compare it against my sons stock Glock 19 at the same time. I'll also try to get some kind of a scale I can measure it with. Would a fish scale give a relatively accurate reading? Anyone ever tried that?

 

[jhearne]

The fish scale might work, would be best if it had a hold feature for max weight. I used a coworker's Lyman (IIRC) digi scale and it worked, but the groove for the trigger to ride in was a little small on the SR9 trigger, wasn't 100% on its reading but after about 5 solid tests I got 11.5 lbs +/- .25 lbs each time.

As for your question about the Trigger and letting go after half pulling, the Striker DOES return back "Home" to it's fully cocked position. Let us know what else you find man.

Josh

 

[mattbren]

I tested the trigger pull today using a fish scale which I verified the accuracy on with a known weight. The average of 5 pulls was around 4.25 lbs.

Here's a photo of the rig used to pull the trigger that shows where it rested on the trigger.

There's a video of one of the pulls here:

http://www.youtube.com/watch?v=AFcN36sdHxs

Even though the trigger weight is great, my biggest concern is still that the trigger will actually stay in place part way through it's travel. I'm not sure what to make of this yet, but I'm worried that it may just be an inherent high degree of friction in the trigger mechanism.

The striker spring and trigger bar spring must be close to equally offsetting each other, otherwise, given no friction, the trigger would spring back when pressure is taken off of it. The fact that it doesn't leads me to believe that most of the 4 lbs of trigger weight I'm seeing at this point must be due to friction. If anyone else, has some other ideas on what might be happening here, I'd love to hear them.

 

[jhearne]

Here ya go MB,

Link to the Video, http://www.youtube.com/watch?v=AFcN36sdHxs

I really think that they're so close to offsetting eachother that the only force your seeing is the Friction of the internals. I looked at some springs online and couldn't find a specific spring within the size provided stock and the one you purchased, not within the length/size needed. If you could find one that pulled in between with a similar length and width, regardless of wire size, you may find what is needed to get it around 6 lbs or so, under 8 would be nice too. Your on to something for sure, keep us posted.

Josh

 

[mattbren]

Josh, thanks for posting the photo. What did I do wrong for future reference?

 

[mattbren]

It's sad really, because if the weight I'm seeing is all due to friction, then a true 4 lb. trigger weight would not be achievable with this gun. I wonder if this has anything to do with the continued delays we've seen from Ghost.

 

[jhearne]

It's possible as for the delay part, I sent you a PM regarding the spring specs you found.

As for the Image posting thing, on Photobucket theres a list of boxes for posting options, use the one with the

tags. Just copy/paste to where you want and presto. Sometimes you need to resize, but that one was fine as is IMO.

 

[hawkeye]

The friction in the trigger pull might be the result of the trigger bar rubbing against the right side of the frame. Josh, if you remember, I took a couple thousandths of plastic off the inside of the frame with 400 grit sandpaper. I did this only where the trigger bar seemed to rub.
I don't have a trigger gauge but my SR-9 seemed to have a lighter pull after I did that plus all the trigger componet polishing.

 

[mattbren]

Hawkeye, thanks for the input. I checked and I've got enough space between the trigger bar and frame to insert a thick piece of paper so I think I'm OK there. The place I've identified the most friction so far is where the end of the trigger bar is actually sandwiched in between the trigger connector and the safety lever. The trigger connector itself is a very stiff spring and is sprung strongly towards the outside of the gun pressing against the side of the trigger bar and pushing it into the side of the safety lever.

What I don't know is if any of this tension/friction goes away once the slide is assembled. There is a cam inside the slide that pushes the trigger connector away from the side of the trigger bar during certain portions of the slide travel. Unfortunately, I can't see inside to see its exact position when the slide is in battery. It has to be rubbing or at least extremely close though in order for the tab on the connector to force the trigger bar downward at the end of the trigger travel. Unfortunately, this is just part of the design and there may be nothing that can be done about it.

 

[gommee]

I found the same thing, but I had wear marks on the Safety tab. Closer examination, I found the Safety tab slightly bent outwards. After I reformed it slightly inward, the drag on the trigger bar was removed and the tension of the trigger reset bar against the trigger bar was less. The trigger reset rests on the safety tab and the tab on the trigger bar goes in between them causing the drag.

 

[mattbren]

I've tried several different weights and rates of trigger bar springs now, and while all of them resulted in lower trigger pull weights, they also all prevented the trigger from returning forward when released part way through the trigger stroke. I'm returning to the stock spring until I can put some more thought and investigation into what might be causing this.

In the mean time, I've done some more polishing per Josh's tutorial, and the "feel" has definitely improved even if the pull weight hasn't.