The state legislature passed a magazine bill limiting magazines to 15 rounds as of July 01, 2013.
If you possessed standard capacity magazines before that date you can keep them, it does not matter if you were in CO or not.
If you choose to follow the law or do not choose to follow the law, that is a matter totally left up to you.
AR15.com does not support illegal activities and any posts to this effect will be locked and trashed from here on out.
Posters will be warned the first time and will receive a time out the second time.
Please do not test me on this.