The King George V class problem was the quadruple mount

Was the Royal Navy's fourteen-inch gun unreliable, or was the problem specific to the quadruple mounting?

The problem was the quadruple mount, not the basic gun design.

The prompt distinguishes the weapon from the machinery that grouped four guns in one turret. The quadruple mount was the source of the reliability problem. Criticism of the calibre or ballistic design alone therefore misidentifies the failing component. The distinction matters when assessing King George V-class gunnery.