I feel there needs to be some clarification here.
Although everything Bailey Guns said is correct- there some exceptions.
Quite contrary to popular opinion, even if you're on parole, it is perfectly legal to own a gun for self defense purposes.
A defendant charged under this section who presents competent evidence showing that his purpose in possessing weapons was the defense of his home, person, and property as recognized by section 13 of art. II, Colo. Const., thereby raises an affirmative defense. People v. Ford, 193 Colo. 459, 568 P.2d 26 (1977).
Doesn't mean you wouldn't get arrested for it, however. Nor would I like to be in the hot seat on that one.

Also, the "ever" part does not exist. After 10 years, your civil rights are restored.
(I) From the date of adjudication to ten years after the date of adjudication, if the person was not committed to the department of institutions, or on or after July 1, 1994, to the department of human services; or








(II) From the date of adjudication to ten years after the date of release from commitment, if such person was committed to the department of institutions, or on or after July 1, 1994, to the department of human services or, if subject to supervision imposed as a result of an adjudication, ten years after the date of release from supervision.
So the amount of time that one had to do really doesn't matter if he's been good for ten years.

And to go past even that, if your civil rights have been restored, then even the feds can't charge you.
Prior Colorado conviction not predicate felony for purposes of federal prohibition of possession of firearm by felon. Defendant was wrongly charged for possession of gun by felon, because at the time of his arrest he was once again entitled to possess a gun. Under this statute defendant's civil rights had been restored ten years after he served time on his prior conviction, such rights encompassing his ability to possess a firearm. U.S. v. Hall, 20 F.3d 1066 (10th Cir. 1994).
The only thing in Colorado that really would sink the ship is a domestic violence.
It is not your job nor your duty to scrutinize this person's background. All that state law says is that you see a valid Colorado ID and that you know of nothing that would bar said individual from legally possessing a firearm.