I have collected guns for 20 years (since high school)and sold them in a retail store while in college and have never seen anything like it. I've asked at SHOT show, I've asked at SCI, i've come up empty. There are no "markings/stamps" that i can find anywhere on the rifle except "38-55 Win", hence the mystery. I really hope that one of ya'll can help.
38-55 bore diameters were all over the place from manufacturer to manufacturer and it is always advised to slug the bore FIRST before you shoot anything in a 38-55, especially a European 38-55..........To compound the chambering issues, 38-55's were made in two length cartridges and shooting the correct length cartridge, i.e. brass case, is more inportant than a couple thou in bullet diameter........
38-55's were made with case lengths
and chambered for 2.125" at first, for MOST early guns, BUT the ammunition and guns were also made,
and still are, with a case length chambering of 2.085" or a little over as standardized by SAAMI.......significant difference between the two. You will find both chamberings in various guns as with the varying bore diameter.
Many of the modern factory ammo case lengths are 2.085" and are the shorter case lengths as dictated by SAAMI......suggest you measure what you have before you shoot the gun any more. New brass is available in both lengths for reloading to the correct chamber size.