We can purchase guns that can hold magazines that can hold greater then 10 rounds we only can use 10 round magazines. We can possess magazines that hold greater then 10 rounds as long as they were manufactured prior to Sept 13 1994. Although we can possess those magazines we can not leagley carry with a magazine that holds greater then 10 rounds. The only time a large cap magazine can be used is at the range or a sanctioned competition. Large cap magazines can only be transported unloaded and in a locked container. So there is almost no reason to have any large cap magazines.