You need to keep the inherit bit.
Put back:
class ctiobjects02_gunfort: t55g
Then in the class definition add:
weapons[]={"WeaponClassName1","WeaponClassName2"};
magazines[]={"MagazineName1","MagazineName2","MagazineName3"};
WeaponClassNAme1 would be the classname of the first weapon your object is using.
WeaponClassNAme2 would be the classname of the second weapon your object is using.
If you are only using one weapon then obviously leave out the second one.
The same idea goes for the MagazineClassNames.
So, going by your earlier example you would have:
class ctiobjects02_gunfort: t55g
{
displayName="Gun Fort";
vehicleClass=CLASSNAME;
maxSpeed=1;
model="\ctiobjects02\gunfort";
fuelCapacity=0;
hasDriver = false;
hasGunner = true;
hasCommander = false;
forceHideGunner = true;
forceHideDriver = true;
forceHideCommander = true;
transportSolider = 0;
weapons[]={"WeaponClassName1","WeaponClassName2"};
magazines[]={"MagazineName1","MagazineName2","MagazineName3"};
gunnerCanSee = CanSeeAllButRadar;
commanderCanSee = CanSeeAllButRadar;
armor=1000;
This means your object inherits all values from t55g EXCEPT the ones you have stated yourself, these will override the values stated in the config for the t55g.
Planck