Have you removed the bumper to see if there is a weight bolt?
I have a different model that is 19oz with no weight bolt, I don’t mind the weight as much the balance point which for me feels a bit butt heavy.
I don’t mind the extra weight of the extension, I don’t leave it permanently, only for reaching far shots.
If there is no weight bolt, maybe a custom cue maker can bore it a bit but I would not bother with such low end cues.
