Why a corrected T7 .60-calibre gun would still yield to 20 mm cannon

If the T7 .60-calibre aircraft gun had been debugged, would it have lasted into early jets?

It might have served briefly, but 20 mm cannon offered enough additional effect to replace it eventually.

Correcting the T7 prototype's faults could have won the .60-calibre weapon a limited period of service. The panel nevertheless expects it to be replaced rather than become a long-lived standard. A 20 mm cannon gains more than a small increase in diameter because projectile volume and effect rise disproportionately with size. The answer uses the square-cube relationship to explain why a perfected heavy machine gun would still struggle against true cannon armament in the jet age.