Turret armament weight and firepower tradeoff

The turret fighter needed enough firepower to make its wide firing arc dangerous, but heavier weapons intensified its central weight problem. A turret armed with 20 mm Hispano cannon could have shredded an approaching aircraft from any angle within its field of fire. That threat might have forced opponents to remain outside the turret's effective range. In practice, the aircraft carried .303 machine guns because a cannon-armed turret would have been still heavier. The larger weapons would also have made an already cramped fighting position harder to operate. Reducing weight also reduced the combat value that was supposed to justify carrying the turret.