I have a 3 year old glock 23, around 250 rounds through it, and a police trade in 27 (new recoil spring), with who knows how many through it, that both choke on Blazer Brass 180gr FMJ. The rounds dont even make it out of the magazine, as the slide "pins" them at a horizontal angle in the mag and jams. A hard rap on the back of the slide will not force it to go into battery. The jammed round doesnt even get a chance to go into battery . Racking the slide back and releasing it will load the jammed round normally. The jam occurs about once a magazine, and just to be sure it wasnt the mags, I used the latest, brand new, Glock "1" 40 caliber magazines today. No limp wristers were involved in shooting. Have NOT had a chance to try different ammo yet, but will soon. Any one else see the same?