I only have 7. I have guns in .22lr, 9mm, .40 S&W, .357 SIG, 10mm, 45 ACP, 5.56, and 7.62x39. I feel I have a very well rounded selection of calibers and don't see any gaping holes in my options. However, there's nothing wrong with having more. I am sure somebody here has more than 20 different semi auto cartridges that they have guns for, Who is it?