Remember the line about how no magazine may be sold in this state that can be "readily converted" to hold more than 15 rounds? It now appears that most magazines have extensions available for them that would make your stock 15 rounder illegal because you can slip a 2-round extension onto it.
Colo Peak Politics has a story with an accompanying video that explains the latest SNAFU. Short version:
OUR VIEW: Best case, the Mag Ban bill, HB1224, was rushed. Worst case, it was drafted by a liberal on quaaludes who has never shot a gun.The bills sponsor is in the video. When I saw her at the judiciary hearings it was painfully obvious right from the start that she had not even read the bill. Rep. Rhonda Fields recognizes that there may be problems with the bill but hopes people will "just comply with the law" in spite of some little plastic thingie.
After Jul 1, you will be able to buy a centerfire pistol in Colorado, but probably not a magazine to go with it since most of them are amenable to extenders. For that you need to drive to a bordering state.
Now that there is a thick layer of band-aids on the bill to prevent your Mossberg 500 from becoming an "illegal magazine" in its own right, and another page of exceptions to allow Magpul and its suppliers to make standard capacity magazines as long as they don't sell them to the natives, it seems that this bill will effectively prevent the sale of most common handguns as long as the small plastic extenders exist. Note that the extenders are not banned, just the mags.
The above description of the bills author is beginning to look charitable.