Hex screw holding bumper goes into a weight bolt.
The cue certainly looks like an American Made custom, but who made is the question. It may be very difficult to identify the maker, the weight bolt is a standard style used by Cue makers for many year's, along with the Allen Head screw that held the Bumper on.
I suspect that unless you get luck you may never know who made this cue, so lets hope you get lucky and some one can positively identify it.
Take care