This function checks whether the player still has enough ammunition for another attack with the current weapon. If not, it starts a weapon change.
This code is taken from Doom 2's SuperShotgun. A_CheckReload is called to check to see if there are any more shells left before starting the "reload" animation of the super shotgun.
Fire: SHT2 A 3 SHT2 A 7 A_FireShotgun2 SHT2 B 7 SHT2 C 7 A_CheckReload SHT2 D 7 A_OpenShotgun2 SHT2 E 7 SHT2 F 7 A_LoadShotgun2 SHT2 G 6 SHT2 H 6 A_CloseShotgun2 SHT2 A 5 A_ReFire Goto Ready