My bullet go anywhere if I aim a part, how to fix this?

My bullet go anywhere if I aims a part, is it a problematic because is a little the aim of game and I don't know how to fix this problem:/ so can someone help me? Thank for your answers and your explanations:)

Gyazo GIF

function makingBullet()
    local bullet = Instance.new("Part", workspace.Debris)
    bullet.FormFactor = "Custom"
    bullet.TopSurface = 0
    bullet.BottomSurface = 0
    bullet.Anchored = false
    bullet.CanCollide = false
    bullet.Size = Vector3.new(0.1, 0.1, 1.8)
    bullet.Material = 'Neon'
    bullet.BrickColor = BrickColor.new('Daisy orange')

    local Script = script.DamageScript:Clone()
    Script.Parent = bullet

    game:GetService('Debris'):AddItem(bullet, 10)

    return bullet
end

function NPC_Module.FireBullet(mouse, player)
    local bullet = makingBullet()

    player.Character.Header.AimPart.Shot:Play()

    bullet.Name = player.Name
    if workspace:FindFirstChild('Debris') ~= nil then
        bullet.Parent = workspace.Debris
    else
        local DebrisFolder = Instance.new('Folder', workspace)
        DebrisFolder.Name = 'Debris'
        bullet.Parent = DebrisFolder
    end

    bullet.DamageScript.Disabled = false

    local BodyVelocity = Instance.new('BodyVelocity')
    BodyVelocity.Parent = bullet
    BodyVelocity.Velocity = (mouse.Hit.p-bullet.Position).unit*120
    bullet.CFrame = CFrame.new(player.Character.Header.AimPart.Position,mouse.Hit.p)
end