Mounting weapons to vehicles isn't even anything to do with Wrench Events.
If you want to make a vehicle with weapons, look at Aloshi's Warplane (mounted gun + rocket drop) or my HE Grenade Bomber (drops five grenades and recharges) plane, the scripts for them are based off the Stuntplane and can be found be searching.
I have an idea on how to make a sort of mounted "Turret" for vehicles (2 players, one driving and one aiming/firing), but there's already one in v9 (the Tank) and I need specialised models to do it.