I'm talking about the gap measured with a feeler gauge at the end of the loop on the trigger bar that engages the nub on the sear. I used smooth jaw pliers to close it slightly.

Closing the loop moves the trigger break rearward. So, in effect, with a stock trigger you have less overtravel but more takeup. If the loop is closed too far, the trigger will stop before the sear releases. If open too far, the sear can release before the trigger bar is rearward enough to fully deactivate the striker block.

There is a Youtube video by Apex showing how to adjust the loop. They recommend small increments.