Custom Rig Pointing Issues

I am currently trying to make my custom rig point towards where I have my mouse but I am having problems getting it all setup. This is what I currently got:

local x, y, z = CFrame.new((char.RightUpperArm.CFrame * old).p, hit.p):ToEulerAnglesYXZ()
char.Torso.RightUpperArm.C0 = CFrame.new(old.p) * CFrame.Angles(x, y, z)

the old variable in the above script is the default C0 of the RightUpperArm

Here is the result

If anyone could help it would be really appreciated