The Janissary range is 575, adding the Damascene Metallurgy workshop tech is an additional 75 for a total of 650 range.
The Legendary Stinger is 650. This makes them the same with workshop addition. The problem is when you put the Janissary in watchtower the color range indicator shows it shorter then when you put the Legendary Stinger in, it goes out farther. So this prove the additional 75 from workshop is not making them the same in distance. You are not getting the 75 extra range addition to the Janissary. You test and see Let me know if you are maybe its just my base problem.