My guess as to the likely cartridges it could be include 8,15x46R, 8x58R Sauer or 8x57R/360. With the 172,28 (.300") mark I think it's unlikely to be a .32 WCF (.32-20) because the .32-20 bullet diameter is a bit small for that in the .312" range.

Scott, If you could post back with the diameter of the rim recess and chamber mouth we could probably narrow it down quite a bit. Also, is the chamber straight or necked?