I replaced my 509 trigger with the Apex kit about a year ago. I keep having issues with the trigger pin walking out toward the right side of the gun away from the takedown lever. It will only walk out a couple of millimeters, and has never gone past that point. No reliability issues in 3,000 or so rounds since I bought it. Simply an annoyance that seems to happen more frequently now. Anybody else ran into this issue, or have any suggestions to fix it? And hopefully without having to remove the ridiculous locking block pin again.

Hmm, sounds like your trigger pin might be very slightly undersized. Apex has excellent customer service. Contact them and they will probably send you a new pin to try.

If you don't want to do that, you could remove the pin, hold the pin on the anvil section of a nice and hit one end of the pin with a ball peen hammer in order to mushroom the head of the pin out a bit. The increased diameter and rough edge of the pin from mushrooming will help hold it in place.

If the pin you are talking about is roll pin, you could also stick an awl into one end of the pin and hit the awl with the pin against a flat anvil surface, expanding the opening of the end of the pin, providing more grip in the hole of the trigger.

I take it you mean the pin that’s a MF’er to get out? That pin should not shift.

I can’t recall if that pin was tapered or not, but as I recall, it went in from one side only. FN presses them in at the factory, and they are not intended to be user serviceable nor reused.

I would review to installation instructions to ensure everything was re-installed correctly, then inspect the frame for any damage. From what I understand, it’s fairly easy to damage the frame performing the operation. Good luck!

ETA: Re-read the OP and realized the locking block pin is what I was referring to above.

Just checked my 509T w/ Apex trigger and noted that I can move the pin with light force  to where it stands about .050” proud of the right side of the frame. Will not move past that point, but also has never drifted on its own.