if the rifle is too heavy it sounds like you bought the wrong rifle! To lose weight the stock will probably be the first thing I would change. I have a .223 with a 181/2" barrel and I am not getting the velocities that a longer barrel would give, it works for me because I am not looking for that but are you?
As to the powders and bullets n130 and n133 are classic .233 powders and n140 if you decide to go with heavier bullets.
Work each bullet weight up on its own at the moment you are trying all of them and your reported loads are not in any real order .
The scope mounts you need to sort out packing is not a sensible way forward in the long run.