Just because I own a gun in .455 Webley Automatic or .22 Remington Jet doesn't mean I need to keep a bajillion rounds on hand for it.
I have a whole bunch of .22LR, .38, 9mm, and .45ACP, because that's what I shoot the most.
.22 Remington Jet, .25 ACP, 7.62x25, .32 ACP, .32 S&W, .32 S&W Long, .32 H&R Magnum, .38 ACP, .38 S&W, .357 Magnum, .40 S&W, 10mm Auto, .41 Magnum, .44 Special, .44-40, .44 Magnum, .45 Colt, and .455 Webley Automatic, I don't stock up on as much, and may only have anywhere from half a box to a couple hundred rounds.