I see. You're listening to the wrong people. The Sherman went through several gun changes. But you also need to understand it's a medium tank. It was never originally intended to take on heavy tanks. It's job was infantry support and to counter artillery and other medium tanks. Which it did. It was designed in 1940 using 1930s concepts of war and tanks. This is not a technology divide. This is a strategy and time divide. You're also wrong on why later German tanks were created. They had different roles. Medium vs heavy vs the always evolving theater changes. This also drove gun changes in the Sherman and other tanks by all, and guns fielded by America and Germany. The bulk of Soviet aircraft were shit. Most were WWI or slightly after. Casualties were high because they sucked. The donated Airacobra was American and influenced their other designs. Its cannon allowed it to be an effective tank buster. Only late in the war did their numbers of good aircraft rise. See originally stated reasons. They had the luxury of designing based on what they had experience of what worked. Whereas Germany was over extended and pushing in the wrong areas. Even Japan was developing better aircraft than the Soviets. Rockets were an American invention. See Robert Goddard. The Germans were the first to embrace. The Soviets and Americans followed. You'll even find rocket racks for Shermans. The good Soviet tanks were designed almost a half decade after all the others. But they entered the war late for a variety of reasons. All with the benefit of observing modern war to drive the design.