I am one of those who plays with the 8.15x46R cartridge. Although supposedly "normalised" many years ago, there are quite a few decidedly different chambers for the several variants of this cartridge. I have re-visited the gunsmith's chamber drawings and 8.15x46R now makes sense. Forget the Peterlongo or Collath suggestions. Those are in error. What first appears to a bottleneck for the forward end of the chamber for a high velocity hunting cartridge is the "forcing cone" peculiar to the 8.15 cartridge.
The gunsmith's chamber cast is OK, except that he did not extend the chamber cast far enough into the barrel. You need bore & groove measurements about an inch in front of the forcing cone and another set near the muzzle. That will help you with bullet selection.
The 8.15 cartridge is normally fired with cast bullets, but RWS made a load with a jacketed hunting bullet. You can read all about the 8.15 cartridge and "stop-ring" bullets on the ASSRA Forum.
Don't be in a hurry to re-barrel it. There are quite a few guys who shoot the cartridge. Yesterday, I shot in an offhand match for single shots & lead bullets, 31 shots at 200 yards. Of the 7 competitors, 2 used the 8.15x46R.
