Anyone using that formula must have either (1) known that the formula was inaccurate at that airspeed, or (2) denied the existence of supersonic shells and bullets.
Likewise today, we know something is wrong with the combination {relativity, quantum mechanics} because if our formula for both were completely true, the universe wouldn’t exists.
The supersonic munitions of the era were rather difficult to ignore, so you need better evidence to claim PhDs would’ve laughed at the idea, than merely that the best formula they had at the time was not good enough.
Likewise today, we know something is wrong with the combination {relativity, quantum mechanics} because if our formula for both were completely true, the universe wouldn’t exists.
The supersonic munitions of the era were rather difficult to ignore, so you need better evidence to claim PhDs would’ve laughed at the idea, than merely that the best formula they had at the time was not good enough.