Actually yea, this was a resin cast of an old metal FH run, one where they screwed up the rear chamfers and made them bullet shaped.
I puttied up the holes, and this was back when I didn't understand you needed MORE material to then sand flush. I screwed up basically, and am really glad it gives off that impression!
I puttied up the back too, sealing it to the aluminum scratch-made bull barrel. I've been wanting to replace it with a Field Marshal one, since its the only resin thing left on the gun (aside from the rubber bumper piece, which is a cast... real pistons with putty inside them, etc)