I've had two Type 38 Arisaka's for 3 or four years and never had fired them till last Friday. One is a very nice custom Monte Carlo stocked with scope and shortened barrel and turned out to be a nice shooter. The other is a good condition long rifle with good bore but stock has been shortened. This one is the headache! I shot one round and then looked at the fired brass and discovered the shoulder had moved "1/2 inch" forward! Scary! I have ordered some Cerro-Safee to do a chamber cast. That being said I thought I might share a pic of the brass. The first brass is a normal 6.5x50 Norma round, third brass is a normal fired round in my second rifle. The second brass is the problem brass fired from the long barreled rifle. I believe the rifle has been converted to something??? Couple shooters, at the range, suggested it may have been chamber bored to a .257 Roberts or a .260 Rem. I do have a .260 Rem brass and it would only chamber 3/4 of the brass's length so pretty sure it's not .260 Rem. Don't have a .257 Roberts brass to try. Maybe someone has ideas of what a popular conversion might have been utilizing the same barrel.