I have G17 full cap mags with glock extensions. the ones I have bought over the last couple years all hold 20 rounds. the ones I just bought from glockmeister hold only 19. glock has changed the follower...the old ones I have are 9mm3 the new ones are 9mm5 and look much different. called glockmeister, they dont understand it either and dont have any of the old followers. any ideas?