I got a GPT back when they first released for my Gen 5 19. I rarely carry/shoot that 19, so I wanted to swap it over to my Gen 4 22. I swapped out the ejector and installed.

While function checking and manually cycling, I noticed that when I held the trigger to check reset that the slide stop was being pushed up as if there was an empty magazine in the gun (was cycling with no mag). I was using a Kagwerks slide stop and managed to forget to check this with a factory slide stop, but there is no difference inside the gun. It seems like the trigger shoe is actually pushing up on the slide stop, but I can only see this after the stop is pushed up.

I have also noticed that the current offerings for the GPT say for gen 4 and 5 whereas mine was labeled gen 5 only. I vaguely remember something about there being some change to the GPT from the original version.

Can anyone explain to me what the change was? If the solution is for me to just go buy a new "gen 4/5" marked GPT, then great I'll go do that. And I figure that is likely the solution here. I would just like to know what the change(s) was/were.

My original GPT and both of my Version 2's do it as well.  It never caused any issues with the pistol functioning and or shooting.  It would only display this when I locked the slide to the rear, removed the magazine and tried to cycle the slide.  The slide stop wouldn't fully disengage.  It has something to do with the trigger shoe itself and it's design.  

FWIW, I am running a Ranger Proof VEX shoe on one of mine now, and  that GPT doesn't hold the slide lock.  I didn't change the shoe because of that, but it not holding the slide lock is a byproduct of the shoe change.  I also highly recommend changing to the VEX shoe.  It make the GPT feel like a whole different system, in a good way.  I changed the shoe to reduce trigger reach since the GPT flat shoe is overly fat.  It extended the trigger reach even more than the standard Glock curved shoe.  The VEX shoe provides me with the shortest reach possible without  bypassing any of the safeties.

The change they made to the V2 is they are using the standard Glock connector instead of the dot connector.  It gives a descrnable wall now instead of the rolling type break.  I suspect they changed the trigger return spring as well, as the trigger safety tab no longer catches on the frame like it did in the original version.  I can't confirm this, but that would prevent the safety tab from catching.  I have the trigger shoes from both versions and I can see absolutely zero difference between them, even with caliper measurements.  They also provide a Gen 5 plate so it can be used in the Gen5 and Gen 4 pistols.  
TXPO

I have an original GPT with the Vex shoe and don't see any movement of my factory slide stop.  I've fired a few thousand rounds through it with no issues.  I tested a dot, minus, standard, and a + connector and none had issues.  I ended up using a standard connector with it and get around a 4lb pull tested with a Wheeler digital gauge.  

I've tried a lot of Glock aftermarket triggers over the years and the GPT with the Vex shoe is my favorite setup.

I agree.  I am running the same setup, and IMO, this is the best general purpose trigger setup for the Glock.  





TXPO

I appreciate the feedback! I am going to order a VEX shoe and see how it goes.