No, large-capacity gun magazines are not illegal in Colorado. There is no state law banning them and they can be freely bought and sold within the state. However, Colorado does have a law banning the use of large-capacity magazines in certain situations. For example, it is illegal to use a large-capacity magazine in the commission of a crime or in a way that endangers public safety. So while large-capacity magazines are not technically illegal in Colorado, there are some restrictions on their use.
Robert Answered question September 2, 2022