NEWTOWN - The country’s largest gun organizations and the largest gun-owners group in Connecticut are rallying behind the nation’s oldest gunmaker in fighting a wrongful death lawsuit brought by families of 10 Sandy Hook shooting victims. The National Rifle Assocation, the Newtown-based National Shooting Sports Foundation and the Connecticut Citizens Defense League are among the groups intervening in state Supreme Court on behalf of Remington, the maker of the AR-15-style rifle used in the 2012 massacre of 20 first-graders and six educators at Sandy Hook School.