Well seems this one is a little harder than I thought it would be.
It's a MK.7 16"/50 Cal. (406 mm) APC (Armor Piercing, Capped) Shell like was used abourd the US Iowa Class Battleships in WW2.
MK.7 APC SHELL SPECS:
An upgrade from the 2,240 lbs. AP shell used in the South Dakota and North Carolina Class Battleships - The Mk. 7 APC (Armor-Piercing, Capped) shell weighs in at 2,700 lb (1225 kg) and was designed to penetrate the hardened steel armor carried by foreign battleships. At 20,000 yards (18 km) the Mk. 7 could defeat (penetrate) 20 inch (500 mm) of steel armor plate. At the same range, the Mk. 7 was able to penetrate 21 feet (6.4 m) of reinforced concrete.
In comparison - the specs for the MK. 13HC (High Explosive) round for the 16"/50 cal. guns of the Iowa's.
For unarmored targets and shore bombardment the 1,900 lb (862 kg) Mk. 13 HC (High-Capacity—referring to the large bursting charge) shell was available. The Mk. 13 shell would create a crater 50 feet (15 m) wide and 20 feet (6 m) deep upon impact and detonation, and was capable of defoliating trees 400 yards (360 m) from the point of impact.
