As in going to the hangar and selecting gun ship or field?
Yes. You are "manning" the gun as would "man" an airplane or tank. You go into the hangar and choose "Gun Ship or Field". You then get a map of the guns that are available. You select the gun you want and then launch.
In some guns, like the 88's, you can select Armor Piercing or Anti-Aircraft shells. For the AA shells, you can select range by using the C and V keys (I think), and the shells will explode at that range.
Late in WWII, the U.S. developed proximity fuses for the five inch AA shells, which are used in game by the five inch ship guns.
As always, it takes some practice to get the lead on the target right.