yes the only reason it is illegal in the state of Co is the mag however Denver has more restrictions against it Denver " All semi-automatic pistols that are modifications of rifles having the same make, caliber, and action design but a shorter barrel and no rear stock or modifications of fully automatic weapons originally designed to accept magazines with a capacity of fifteen (15) or more rounds." budsgunshop.com/catalog/feeds/state_reg/colorado_restrictions.pdf

Brent, the 15rd Magazine is the main reason and Brace following up Sir.