You may be eligible to possess a firearm in CO according to CO law. However, if the crime was punishable by more than 1 year imprisonment (typically the basic definition of a felony) the answer is "No" according to federal law, regardless of what state law says.
From the www.atf.gov website:
(B5) Are there certain persons who cannot legally receive or possess firearms and/or ammunition?
Yes, a person who –
(1) Has been convicted in any court of a crime punishable by imprisonment for a term exceeding 1 year;
That is also exactly how the question is asked on the 4473.
Just my interpretation of what state and federal laws state. You should probably talk with an attorney regarding possible federal issues in possessing the gun you already have.