i have 150 rounds through my g29 in it's stock form. i recently installed a wolff 21lb recoil spring and went to the range with 180gr underwood ammo. see pics below. i never examined any casings from the g29 in its stock form, so i don't know if it's been happening from the beginning. but i had another g29 that never showed any of these marks. so i'm curious what could be causing the dent and scuff marks? i'll go back monday to try it with the stock recoil spring, but i suspect it'll still be showing up.