I think that is the way it works right now, but it is logical to ask for assistance, considering new players do not know every detail about the game yet... Would be nice to hear about it from developers/gms.

Well, I bout firebird/freez weapon first, and then I bought tank kits, including upgraded versions of some weapons. I bought all 3, but my freez weapon didn't get upgraded (as well as tanks). Any way to fix it?