Speed of M10 GMC (US Army)

[RERomine]

Originally Posted by Marek_Tucan

For ballistic performance, both 3in and 76mm guns are the same, as they were designed to be so - 76mm is just 3-incher with new breech and shorter (but wider) ammo cases so that it is possible to operate it in Sherman turret.

The reference I saw gave the impression the rounds were interchangeable, but did also mention the cases were different. A shorter breech on the Sherman gun makes the case was shorter and wider, but it sounds like both had the same amount of propellant. In that case, the rounds wouldn't be interchangeable. Still, they would have had the same penetration. As I understand it, both guns were based on the 3in flak gun. Seems to be a common relationship between flak and tank guns during WWII.