Last week my brother and I took a war-trophy Arisaka Type 38 Carbine to the range to shoot. The gun came back from the Pacific w/my grandfather, and my dad says that a number of my grandfather's buddies used it in deer camp for a # of years. I detail stripped and cleaned 40 yrs of grime off it some time back, and everything appears fine. W/the bolt removed, hand chambered rounds fit flush w/the chamber, tho there is a little side-to-side play. We loaded it w/new Norma 139 gr ammo at the range, and I let my brother have the first shot. When we checked out the ejected case, the case wall had bulged near the base, abt 3/16 up from the groove. I measured it at 0.455", which is listed as the mil spec case's base diameter in one of my books. Unfired brass at the same point measured 0.444", so there was abt 0.011" expansion. Is this enough to worry about?
I've read a few similar accounts on various boards abt folks with oversize (not reamed) chambers in Arisakas, and that Norma brass may be a bit small. I thought perhaps it had been rechambered to the 6.5-.257 Roberts wildcat, which was apparently pretty common for Arisakas back then, but the a) chamber dimensions don't match (i.e. dia too small), b) my dad said my grandfather never reloaded and c) he'd never seen any of that ammo around the house growing up. There was no evidence of excessive pressure that I could see, and no other case deformation (length, neck dia and shoulder all as unfired).
I've read a few similar accounts on various boards abt folks with oversize (not reamed) chambers in Arisakas, and that Norma brass may be a bit small. I thought perhaps it had been rechambered to the 6.5-.257 Roberts wildcat, which was apparently pretty common for Arisakas back then, but the a) chamber dimensions don't match (i.e. dia too small), b) my dad said my grandfather never reloaded and c) he'd never seen any of that ammo around the house growing up. There was no evidence of excessive pressure that I could see, and no other case deformation (length, neck dia and shoulder all as unfired).