I recently loaded up 500 rounds of .40 cal., 155 grain, lead semi wadcutters, using new, primed, Federal?

br, with 5.5 grains of W231 powder. I use a progressive reloader, a Dillon 550. I fired 50 of the rounds thru my S&W 411 with no problem. A friend fired three rounds out of his Glock 22. The 4th round blew up in the gun. The blast pushed the primer out of the case and blew a hole in the side of the case. I thought I'd overcharged a bullet but my reloader, still set up for the .40, throws the correct powder charge. A double charge overfills the case, so that isn't the problem. OAL of the rounds is within spec. I did discover a crimping problem. My crimping die was fouled with old lead and put an excessive crimp on a number of rounds. I discarded these. I went back to the range, fired 50 more rounds out of the S&W with no problem. Yesterday, my Step Son showed up with his new Glock 22. We go to the range, he shoots five rounds, the 6th blows up. The blast blew the bottom completely off the case. I am stumped. Did I miss some other problem? Appreciate any suggestions.