Well, you have a narrow series of options it seems to me. You might be able to chisel a piece of wood out of the bottom of your patchbox large enough to glue it in, let it set, trim it to shape, and stain and finish. It’ll show some. You can nosecap it. You can reshape the end and do a full refinish. You seem to have plenty of wood at the muzzle. You could contract someone to do any of the above for you. Or you could leave it. I might touch it with some stain for now and make a sober decision after squirrel season.....