...Is legal as long as you don't possess any magazines with a capacity of more than 21 rounds. :(
A 30 round magazine magically converts your semi auto center fire rifle into an "ASSAULT WEAPON" :angry:
http://www.rmgo.org/gun-law-faqs/assault-weapons (http://www.rmgo.org/gun-law-faqs/assault-weapons)
Can I legally possess a semi-automatic, so-called "Assault Weapon" in Colorado? CONDITIONAL YES. Some municipalities ban them or require their registration. Though SB03-25 was designed to remove these municipal restrictions, a November 2004 ruling (http://www.rmgo.org/alerts/2004-denverruling.htm) by Judge Meyers kept the Denver ban in place (though modified).
Note: In January 2007, the Denver City Council passed 38-07, which modifies Denver's assault weapons ban.
What is an "Assault Weapon"? Colorado law does not define an "assault rifle" or "assault weapon". Click Here (http://www.youtube.com/watch?v=X9cDbA8O9-c) for a short video that may help you understand the difference between a full-auto rifle and semi-auto rifle (Note: the narrator of the video misstates that fully automatic firearms are illegal -- please see our NFA weapons FAQ section (http://www.rmgo.org/#NFA).
Does the City of Denver have an Assault Weapons Ban (AWB)? YES. Section 38-130 of Denver’s Revised Municipal Code (http://www.rmgo.org/DenverOrd.shtml) was amended in 2007 and is titled “Assault Weapons” Denver's Assault Weapon ordinance (as well as other firearms ordinances) can be viewed here (http://www.rmgo.org/DenverOrd.shtml). That ban, however, only applies to firearms with magazines that hold more than 20 rounds.
NOTE: This means it is legal to own an AR-15, FNFAL, HK91, MAK90, etc, as long as you do not insert a 21+ round magazine.
Does Denver’s AW ban specific firearms? NO. Denver had a list of specific weapons that were banned but the 2007 amendments eliminated that list. For example, Denver’s old law banned the Colt AR15 by name. That weapon and all others on the previous list are now allowed in Denver with certain exceptions – namely those weapons with a high capacity magazine of 21 or more rounds. So, an AR15 with a 20 round magazine is not considered an "Assault Weapon" by Denver's ordinance. That same rifle with a magazine with a capacity of 21 or more rounds is considered an "Assault Weapon.".
Does that mean that I can own a so called Assault Weapon in Denver? CONDITIONAL YES. There are limitations on what you can own. Generally, Denver’s new law bans the possession of both high capacity magazines of 21 rounds or more and all rifles with a magazine of 21 or more rounds, which makes it an "Assault Weapon" in Denver's eyes.
Does Denver ban shotguns as well? YES. Any semi-automatic shotgun with a magazine capacity of 6 or more rounds or a folding stock or both is also considered an AW.