Raimey;
Sorry, I got confused there. I was thinking the 8x57R/.360 was the 8x57JR case necked up to hold the larger bullet. You are right it is actually the old 9.3x57R case necked down to hold the .318" bullet.
The 9.3x57 case is a straight taper case similar to our .38-55 case but longer. Necking it down the take the 8mm bullet gives it a slight bottleneck.


Miller/TN
I Didn't Say Everything I Said, Yogi Berra