My 14 magazines have different combinations of springs and followers, but some hold 20 (very tight), four hold 20 (easily reloadable) and a few hold 19. I have mixed and matched Taran followers and springs, Grams, Dawson, stock etc. and the ones that hold 19 will still hold only 19. the same with the ones that hold 20. There is one I can get 21 in, but it can only be loaded with the slide locked to the rear. I have measured and examined and still cannot tell why some hold more than others.