How do I make a cannonball always shoot in the direction of the muzzle?

Recently, I've been learning how to script, and so I decided to make a simple cannon that fires whenever you press a trigger block. The problem is, I want the velocity of the cannonball that it launches to always be towards the direction of the muzzle. How do I go about doing this? Or is there a more efficient method?

gun = game.Workspace.Cannon
trigger = game.Workspace.Trigger

db = false
function fire()
    if gun == nil then return end
    if db == false then
        db = true

    local projectile = Instance.new("Part")

    trigger.BrickColor = BrickColor.new(1004)

    projectile.Position = gun.Position
    projectile.BrickColor = BrickColor.new(1003)
    projectile.Shape = "Ball"
    projectile.Size = Vector3.new(3,3,3)
    projectile.Material = "Metal"
    projectile.Name = "Cannonball"
    projectile.CanCollide = false
    projectile.Velocity = ???

    projectile.Parent = game.Workspace

    wait(5)
    trigger.BrickColor = BrickColor.new(1020)

    db = false
    end
end

script.Parent.Touched:connect(fire)