I'm a little surprised that the PMC wouldn't cycle but it is Korean. It seems that Glocks take about 200 rounds to break in. I've shot new Glocks with the Winchester white box bulk ammo with no problems. In my G34 - I loaded crap brass with Winchester 231 4.5 ~ 4.6grains, CCI or Winchester SP primers, and 115gr FMJs. That was plenty even in a new pistol.
My 8yr daughter shoots mine and can manage not to limp-wrist... That's all I have to say about that.
As far as the brass tumbling... If you want to mix brass, get the
Lyman brass baggie It keeps the brass separate.
Give her a chance - you'll like her.