Otto,
It seems that if you made cases from 30-30 brass,it would make life a lot easier for you.The nominal rim thickness for 30-30 is .063", which is about right for your rim recess(a couple thousanths to allow for tolerances).Also you could make the shoulder wherever you want it, w/o shim.I went back to the first post, and didn't find if you slugged the bore.In the first posting, you showed the proofmarks, which included 172,28. This is the bore diameter(not groove/bullet dia)as expressed in guage measurement, used before 1912( your rifle was proofed in Zella-Mehilis in Aug 1911). This equates to about 7.62mm,which is about .300".This would fit very well with the .312" bullet diameter of 32-20 (and 32 S&W long).BTW groove diameter in other 8.15x46R rifles varies, maybe up to .338",therefore the concern.If you don't already have a 32-20 reamer, you should be able to "single point" a 32 S&W long chamber in your adapter.
Mike
