Activated in 1953, the Presidential Salute Battery is equipped with ten 3-inch Gun M5s which have been mounted on M6 howitzer carriages.
The M5 is a World War II-era anti-tank weapon.

The battery renders gun salutes according to a customary order of arms which is 21 rounds for heads of state (including the president of the United States and former presidents); 19 for the vice-president of the United States, foreign chiefs of government, and members of the cabinet of the United States; and 17, 15, 13, and 11 for flag officers of the rank of O-10, O-9, O-8, and O-7, respectively.

Under an 1890 regulation issued by the United States Department of War, the "Salute to the Union" consists of one round for every state of the United States, or 50 rounds since 1959; it is fired by the battery annually at noon on U.S. Independence Day.
The Presidential Salute Battery fires blank artillery rounds packed with a 1.5 pound powder charge.
Activated in 1953, the Presidential Salute Battery is equipped with ten 3-inch Gun M5s which have been mounted on M6 howitzer carriages. The M5 is a World War II-era anti-tank weapon. 
The battery renders gun salutes according to a customary order of arms which is 21 rounds for heads of state (including the president of the United States and former presidents); 19 for the vice-president of the United States, foreign chiefs of government, and members of the cabinet of the United States; and 17, 15, 13, and 11 for flag officers of the rank of O-10, O-9, O-8, and O-7, respectively.
Under an 1890 regulation issued by the United States Department of War, the "Salute to the Union" consists of one round for every state of the United States, or 50 rounds since 1959; it is fired by the battery annually at noon on U.S. Independence Day. The Presidential Salute Battery fires blank artillery rounds packed with a 1.5 pound powder charge.
Presidential Salute Battery