I understand that Denver bans "assault" weapons.. The specific wording I am concerned about is:

All semiautomatic action, centerfire rifles with a
detachable magazine with a capacity of twenty-one (21) or
more rounds.

So, does that mean that if I have an AK-47, AR-15, ect, but only own 20 round magazines, am I legal? Or does it mean that just because it is CAPABLE of taking a 30 rnd magazine it is illegal, even if I dont own any 30 rnd magazines?

I just moved to Denver, and need clarification please?