Bomb, Practice, Mk 15, Mod 4, US Navy (Dummy/Inert)
This is a Cold War/Vietnam War-era Practice Bomb Mk 15 Mod 4 as used by the US Navy for aerial bombing training. It is inert, and would be filled with sand or water. A flash tube, which would extend throughout its transverse axis, would house a pyrotechnic signal and firing pin assembly to detonate upon impact to mark its landing relative to the target.
The Mk 15 is made of welded sheet metal. The empty weight is ~17 lbs. When fileld with water (4.55 gallons) it weighs ~56 lbs, and ~95 lbs when filled with wet sand. Under icing conditions, a mixture of anti-freeze could be used instead of water. The overall length was ~41 inches with a diameter of 8 inches. It has a manufacturing date of March 1965.