I am unable to provide a screenshot, sorry, my laptop doesn't have a print screen function.
Its a simple error is text, it says that it costs 2 blueprints to unlock a new machinegun and 1 to unlock a heavy weapon. The reverse is true. Heavy weapons cost 2 and machineguns cost one. I hope it doesn't change as it make more sense to me, hope it was just an error in code/text.