Hey your welcome!
@NoyaN

@AircraftoftheRedStar It's works! thank you so much

This is pretty easy to achieve. First make sure that the first cannon to fire have the salvo delay that you want, then put the firing delay on all the rest of them to 0 seconds. You will have to do that part through XML editing. Also, there is an issue where the cannons with 0 second delay will have no cannon recoil visual; it will exhibit the recoil force, just the barrel will not roll-back like it should.