Republicans are moving fast to repeal gun-control legislation Colorado Democrats passed two years ago in response to mass shootings. The GOP hopes they’ll have the momentum necessary to succeed with more members at the statehouse. Among the first bills introduced when the legislative session started this week were measures to strike laws that limit the size of ammunition magazines to 15 rounds and require background checks on firearms sold online and between private sellers. After November’s elections, the state Senate is under Republican control for the first time in 10 years. But Democrats still control the House, making repeal efforts difficult. At the very least, however, the repeal bills put Democrats in the awkward position of revisiting what has been a thorny topic for their party.