I suggest making changes based on the second and third tests to keep historic as well as balance. That is, while adding weapons to the techtree, the map preferences of the weapons are still remained, and and set the priority of the map preferences above the techtree. Of course, the map preferences should serve as a standard for pursuing historic. For example, MP3008 is a first tier weapon, but according to history, its map preference should dislike maps except Berlin. If you use it, you will only be assigned to Berlin. Since it is a first tier weapon, your opponent in Berlin is also Soviet army with first, second, or third tier weapons that prefer Berlin. This can make various weapons of the same tier appear in different maps and appear more frequently, and avoid some early powerful weapons disappearing irretrievably on the map they should have appeared. For example, as a top tier machine gun, the early version of the MG42 can prefer Moscow, so it is more likely to appear in Moscow’s high level competition, while the MG45 and MG15 will only appear in Berlin’s high tier rooms. Therefore, I believe many players will continue to play the former, after all, under this system, Moscow can only have two or three kinds of tier five weapons, while the vast majority of Berlin is tier five weapons, and the experience is completely different. A bulk of tier five assault rifle from the German army are same as it.
Of course, this combination will dilute people by half, but it should temporarily compromise historicity and balance. How do you think about it?