The Denver lawmaker sponsoring a proposed ban on the sale or purchase of assault weapons in Colorado floated a significant scaleback of the bill Wednesday morning — a move that acknowledged the uncertainty of an impending committee vote. But Rep. Elisabeth Epps said a failure to enact a ban would show that the state’s historic Democratic majorities aren’t serious about the policy. In a lengthy opening statement to the House Judiciary Committee, the Democratic lawmaker told her colleagues that she was contemplating an amendment that would limit the bill — HB23-1230 — to a ban on bump stocks.