Picked up a new Glock 23 Gen 4 last week and after my second visit to the range I have a total of 250 FMJ 165 and 180 grain, plus a number of self defense loads through my new gun and it has functioned flawlessly. Not sure if Glock requires any type of break in but I could not be more satisfied with my 40 S&W, my new every day carry. Not sure of the self defense load, Ive shot Winchester PDX1 165 and 180 grain, Remington Golden Saber, and Speer Gold Dot. They all grouped about the same and I have no trouble with follow up shots. G23 Gen 4 my new best friend.