Well i just thought of this and had to take alook. Im pretty sure this is possible by adding new entries in the .sim files of the weapons. I added in another wpn_cannon entry and nodes etcetc and filled in the bits with the orginal wpn_cannon and made the settings all the same but set it to "AAgun" and the other one for the "Cannon" However it seems that each of the entries points to another set of nodes in the .dat file which i think might also have to be edited but i dont see why ti should... the thing is the game uses the parent id and stuff so you can add nodes together and so on but im not sure that the game allows too differnt nodes the AA fire and Cannon Fire to use the same parent id set in the .dat files. Im going to see what happens if i make a new entry node with the same settings but with a differnt ID then i think it might work as a dual purpose ground + air weapon and this could done for other weapons is well.
But thats if it works.
On another side of things i have been attempting to add a new sound for the 40mm.
So 20mm and 40mm have two differnt sounds, im not sure how to do this ive been playing about in the .dat files and the other files relating to the 40mm but so far no joy, so if anyone knows a thing or two about how to add a sound entries in would be helpful. Ive added the sound for example 40mm.wav into the sh.sdl but not sure on how to overide or get the game to use a custom selected file.
Will update as if i manage to find a way to have dual purpose weapons.