If the Monitor had used larger gunpowder charges in its 11-inch guns, it's likely that it would have holed and sunk Virginia

Shortly after its launch, the Monitor was hustled down to Hampton Roads, leaving little time for testing this novel, radical weapon system. The Monitor was launched with two smaller 11-inch Dahlgren naval guns inside its armored, rotating turret, despite being built to hold two 12-inch Dahlgren naval guns. These were housed in a cylindrical turret that measured 20 feet (6.1 meters) in diameter, 9 feet (2.7 meters) in height, and had an 8 in (200 mm) thick iron roof. A steam engine that could be operated by one man revolved the entire structure around a central spindle.

Each of the 11-inch cannons was limited to employing 15-lb gunpowder charges in order to prevent any catastrophic gun explosion inside the small turret. The 165lb solid shot rounds did a lot to dent and disfigure the armor plating of Virginia even with this lower gunpowder charge. Later testing performed after the war revealed that the Monitor's 11-inch guns would have easily penetrated Virginia's hull at close ranges if it had utilized 25lb or 30lb gunpowder charges.