Pretty rookie mistake I made not too long ago. I bought a fancy aftermarket trigger for my Glock 34, installed it, then put only one magazine down range with it the day before a USPSA all classifier match. Show up to the match the next day and I end up shooting terribly all four stages. The trigger safety (little notch in the bottom of the trigger shoe) on the aftermarket trigger is smaller and starts further down than the stock trigger safety. Since my grip is so high, my trigger finger was not deactivating the trigger safety most of the time. Swapped back to the factory trigger after that. Lesson learned.