Reading through the text of the third reading seems like it is very similar to Denver's laws. Looks like pistols can have 15 or fewer rounds, but centerfire can have only have 10 or less. Other exceptions for tube and rimfire. I am no lawyer though so just my interpretation.

It is a little confusing though, can a non-Boulder resident drive through Boulder with an AR in their car and in a case without any issues, or is that now illegal?