From 1926 until 1986 the standard weapons of the department were the Smith & Wesson Model 10 and the Colt Official Police .38 Special revolvers with four-inch barrels. Female officers had the option to choose to carry a three-inch barrel revolver instead of the normal four inch model due to its lighter weight. Prior to 1994 the standard weapon of the NYPD was the Smith & Wesson Model 64 DAO a .38 Special revolver with a three or four inch barrel and the Ruger Police Service Six with a 4 inch barrel. This type of revolver was called the Model NY-1 by the department. After the switch in 1994 to semiautomatic pistols, officers who privately purchased revolvers before January 1, 1994, were allowed to use them for duty use until August 31, 2018. They were grandfathered in as approved off-duty guns.