My Glocks run factory bbls and, like Glockfan, I've had no problems. I load to 1.135, shorter or longer depending on boolit length, to maintain internal volume (I'm lazy, and leave my measure with the same powder and throw weight for most of my 9 mm loads - of course, fiddling with COAL isn't effortless, and I'm probably not saving much time, but that's me) and subject to feeding characteristics of the assembled round. YMMV, of course.