Quite. You have to be careful, especially during the period before about 1941, when you're looking at the size of a tank cannon to also look at the length of the bore. The T-28, like the T-35, had a 76.2mm gun, but it was a howitzer for firing HE shells. The T-28 would use it against other tanks as well because the tanks of the day were pretty lightly armored, but the primary anti-tank armament of the T-35 was actually the 45mm guns, not the 76.2mm gun in the central turret.