The answer to this question depends on several factors, including the specific capacity of the magazine in question and the state in which you reside. In Colorado, there is no limit on the number of rounds a gun magazine can hold. This means that large-capacity magazines are technically legal in the state. However, it is important to note that different localities within Colorado may have their regulations regarding gun magazines. So, be sure to check with your local law enforcement before carrying one around. Additionally, some states have enacted laws that prohibit the sale or possession of large-capacity magazines. So, if you plan on traveling out of state with your large-capacity magazine, be sure to check the laws of those states before doing so. Thanks for the question!