6x49 Unified High Pressure Test, compared to 7.62x54R it was intended to replace.
Holy crap! Good find!
Now if I could find one stateside…
A compare/contrast between this and the US 6mm SAW from the 1970s is interesting, in that they’re similar ideas, but very different in the details of their execution.
Russian 6x49(ball, HPT, Dummy, tracer bullet) compared with 6mm SAW.