And the vast majority of these were with the Glock 22 in .40SW. 9mm and .45ACP Glocks don't seem to have this problem.
You are correct in that the glock 19 (9mm) KB's are a very small percentage of the guns that do KB. But.... the one i saw personally was a Glock 19. This link has photos of glock 19's which have KB'ed. http://www.thegunzone.com/glock/g19-kb.html