Original Item: Only One Available. This is a fantastic inert drill round for the U.S. 90–mm Gun M1/M2/M3. This was the primary heavy Anti Tank and Aircraft gun used by U.S. forces during WWII and later. It is completely inert, and cannot be converted to any type of explosive device. The shell weighs 23 lbs (5.4kg) and measures 40 inches in overall length.

The shell casing is faintly marked on the side:

Most likely, over the years the shell casing most likely got dented, so it was no longer suitable for loading into the chamber of the gun. However it was still perfectly suitable for ammunition stowage testing.

The bottom of the shell has a dummy fuze marked 10-53, so this would indicate that the shell was made several years after WWII, but the configuration is identical to the WWII type. 

This is an excellent piece of World War II Era artillery and naval memorabilia which will make a very impressive display!

 The 90–mm Gun M1/M2/M3 is an American heavy anti-aircraft and anti-tank gun, playing a role similar to the German 8.8cm Flak 18. It had a 3.5 in (90 mm) diameter bore, and a 15 ft (4.6 m) barrel, giving it a 50 caliber length. It was capable of firing a 3.5 in × 23.6 in (90 mm × 600 mm) shell 62,474 ft (19,042 m) horizontally, or a maximum altitude of 43,500 ft (13,300 m), the M1 can pierce 9 inches (228.6mm) of armor at 1,000 yards with APFSDS ammunition.

The 90–mm gun was the US's primary heavy anti-aircraft gun from just prior to the opening of World War II into 1946, complemented by small numbers of the much larger 120 mm M1 gun. Both began to be phased out in the early 1950s as their role was taken over by surface-to-air missiles like the MIM-3 Nike Ajax.

As a tank gun, it was the main weapon of the M36 tank destroyer and M26 Pershing tank, as well as a number of post-war tanks. It was also briefly deployed 1943-1946, as a coast defense weapon with the United States Army Coast Artillery Corps. Each gun cost roughly $50,000 to make in 1940 and utilized up to 30 separate contractors to manufacture.