I just acquired a Lyman GPR in .54 caliber. Nice looking, all metal is blued steel. Says Lyman Midddletown Conn. stamped top of barrel. Stamped made in Italy with a ser. # a557xxx. Great Plaines Rifle .54 on other side of barrel. Only thing I don't understand is there are no proof marks at all and no year code. There is a large square with a capitol I in it. Anybody know bout these things?