Well the photo looks like a castle nut and tab washer/split pin holding a breech bolt through the forged breech end of an all in one barrel and breech unit and so it may be an old break-down from the middle of the last Century ? But as for the manufacturer I haven't got a clue . Where are Super Lakey and the $6,000,000 I.J. when you need them . Ha ha. Love threads like these . Atb: G.