Description
4"/50 Mark 6 Mod 6 Common Projectile
Item Overview
This unfired, empty 4-inch/50 Mark 6 Mod 6 common projectile is a U.S. Navy ordnance collectible with blue paint and white identification lettering. It belongs to an older naval ammunition family built for guns carried on destroyers and other ships. Its stencils record the projectile model, a black-powder notation, a fuze designation, an ammunition lot, and a Virginia naval depot. These details give collectors several points to study, from early naval shell design to the depot system that prepared and tracked ammunition.
Identification and Features
The designation identifies the projectile as Mark 6, modification 6. That number belongs to the projectile design and is separate from the gun's own mark number. The abbreviation COM PROJ means common projectile, a period Navy class of ammunition. The following white stencil lines are reproduced as supplied, preserving the item's identification and lot information.
- Nominal caliber: 4 inches, or 101.6 mm.
- Finish: blue paint with white lettering.
- Projectile marking: 4"/50 COM PROJ MK 6 MOD 6
- Loading notation and date: L&F BLK PWD 3/12/67
- Fuze marking: B.I.F. MK 10 MOD 4.
- Lot marking: ALN SJ-351-37
- Depot marking: N.A.D ST. J. CR. VA
Function
In service, a common projectile carried a bursting charge inside a steel body. It was intended for targets such as lightly protected vessels and the upper structures of ships. Navy references list a black-powder and TNT filling for the Mark 6 Mod 6, together with a Mark 10 Mod 4 base ignition fuze and an integral tracer. The fuze started the bursting charge after impact, while the tracer helped crews follow the projectile's flight. The rotating band engaged the gun's rifling and gave the projectile stabilizing spin.
Markings Explained
BLK PWD abbreviates black powder and refers to the projectile's historical filling notation. B.I.F. means base ignition fuze, matching the fuze type listed for this model. ALN identifies an ammunition lot, with SJ-351-37 serving as the recorded tracking code. The L&F line pairs the filling notation with March 12, 1967. This is consistent with a depot loading record under period Navy marking rules; it does not establish when the steel body was made. The final line names the Naval Ammunition Depot at St. Juliens Creek, Virginia.
Documented Applications
The Navy's 1947 ordnance reference specifically assigns the Mark 6 Mod 6 common projectile to the 4-inch/50 gun. Official wartime records place that gun system on destroyers, submarines, auxiliary ships, and armed merchant vessels. Navy photographs document 4-inch/50 installations aboard USS Little, USS Ward, and USS Flier. These ships illustrate the parent weapon's range of applications. Their records establish use of the gun type without assigning this particular projectile to any ship or action.
Product History
The Mark 6 Mod 6 reflects an older stage of naval common-projectile design. In May 1947, OP 1664 listed this model as obsolete. The same entry still documented its issue for target practice in blind-loaded-and-plugged or blind-loaded-and-tracer forms. Those versions replaced the service bursting charge with inert filling. These practice versions extended the usefulness of older ammunition designs while crews trained with existing guns.
Equipment History
The 4-inch/50 gun family was already established during World War I. The Navy's 1916 gun reference, revised in 1918, describes the Mark 7, Mark 8, and Mark 9 designs. Later modifications changed liners, rifling, and other details as the Navy maintained and improved these weapons. During World War II, the Mark 12 mount family included dry types for surface ships and wet types suited to submarines. Submarine versions used corrosion-resistant parts and watertight covers. Wartime procurement later shifted toward the larger 5-inch/25 submarine gun.
Weapon-System Background
The 4-inch/50 designation describes a 4-inch bore and a barrel length measured in 50 bore diameters. The gun used fixed ammunition, in which the projectile and a propellant-filled cartridge case formed one complete round. This placed the projectile within a larger system of gun mounts, sights, ammunition storage, and trained crews. Period Navy references show common, high-capacity, illuminating, and target ammunition for the 4-inch/50 family. Each type served a different task, from engaging surface targets to lighting an area or practicing gunnery.
History of Use
Original photographs show the 4-inch/50 gun in both training and wartime settings. In 1918, USS Little fired its port midships gun during target practice off France. On December 7, 1941, USS Ward used its 4-inch guns while attacking a Japanese midget submarine outside Pearl Harbor, before the main air raid. A later photograph shows Ward's No. 3 gun and crew. Another Navy image records USS Flier's 4-inch/50 deck gun at Mare Island on April 27, 1944. Together, these records trace the weapon across World War I destroyer service and World War II surface and submarine operations.
Naval Depot History
The St. Juliens Creek marking connects this projectile's recorded processing history with a long-established Navy ammunition facility in Virginia. The site began naval operations in 1849 and became an important part of the fleet's ammunition supply network. Its work included filling shells, assembling ammunition, storing explosives and torpedoes, and testing ordnance. During wartime, the depot also moved ammunition to other naval facilities in the United States and overseas. Its name on the projectile adds a distinct supply and maintenance history alongside the history of the gun itself.
Condition
This projectile is unfired and empty, with no base fuze or tracer installed. The B.I.F. stencil records a historical fuze designation; no Mark 10 Mod 4 fuze is included. The blue-painted body and white lettering are the identifying finish described for this item.
Ideal For
The combination of model, lot, date, and depot markings makes this projectile a useful addition to collections focused on Navy ammunition and the equipment that supported fleet gunnery.
- U.S. Navy ordnance collections
- Destroyer and submarine history displays
- Naval ammunition identification studies
- Military depot and supply-history collections
Approx length 14", Approx width 4", Approx height 4", Approx weight 30lbs.
Pictures are stock images of our inventory. Unless otherwise noted, you will not be receiving the exact item shown in the pictures. The pictures are representative of the item’s general condition. The item you receive might be slightly better, or worse, condition than was shown in the pictures.
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