Since gramps died last fall we are still going through his gun collection. There is a mauser action barrel stamped 257 mag. It seems there was only the 257 weatherby mag which it seems a lot were built on mauser actions. My ddad seems to remember gramps saying it was a 257AI. If you look in the chamber it doesn't seem as though there is a recess cut for the belt. I saw the 257 wmag was made off a 300hh case so we cut one down below shoulder but it wouldn't chamber..but I am wondering if that was because it wasn't sized. Any thoughts? I was thinking if maybe someone had an empty 257 weatherby mag case they could size and send me to see what this gun is. I would gladly return it. Thanks guys