A large 5 inch BDF Mk 83-0 "Ultrasonic" shell dated to the Vietnam War January 1971 in good to very good condition overall with scattered wear and use marks and surface rust. Weighs approximately 58 pounds. The fuze screws on and off as intended. This item ships, but will not be combined with any other items. The US Navy's Vietnam War-era 5"/38 HC (High Capacity) shell was an iconic 55-pound projectile fired from the legendary 5-inch/38-caliber gun. The "D" refers to Explosive D (Ammonium Picrate), a stable, insensitive high-explosive filler favored to prevent premature in-bore detonation. Fired with nose mechanical-time fuzes (e.g., Mk 58 Variable Time) or Auxiliary Detonating Fuzes (Mk 17/Mk 44) to initiate the insensitive explosive "D". During the Vietnam War, these 5-inch rounds were the backbone of naval gunfire support (NGFS). Firing at high rates, ships like the USS New Jersey (BB-62) and other destroyers dumped thousands of rounds onto coastal targets, forcing enemy troops to break off attacks.