British 15-inch/50 versus American 16-inch guns

Would the proposed British 15-inch/50 have been better than the American 16-inch gun?

Probably against the early American shell, but not after the United States adopted its super-heavy projectile; shell quality drives the comparison.

The British 15-inch/50 never entered service, so the panel bases its answer on the available test information rather than operational experience. Its Greenboy projectile would probably give it an advantage over an early American 16-inch gun using less effective shells. Once the United States introduces the super-heavy shell, the 16-inch weapon is judged superior. The comparison shows that gun caliber alone does not determine performance because projectile design can change the result.