One of the problems I noticed with M 91's and similar was a lack of consistency in caliber, nominally .311 but....... Once upon a time I was reseating .311 Speer bullets in Chinese cases, using the original ball powder, which I hand weighed for consistency. Granted I had a Finn capture with a Sako barrel, but it would do quite well with iron sights.
I would slug the ball to determine the true diameter then try a hunting soft point in .311 or .312 as indicated. You can still get a Lee (kitchen table) kit for the 7.62X54R for a nominal price.
Or, take a chance and try Wolf or similar soft points.
I consider .30-06, .303 Brit, 8X57, and 7.7 Jap in similar class. The rifles do differ greatly.
I would slug the ball to determine the true diameter then try a hunting soft point in .311 or .312 as indicated. You can still get a Lee (kitchen table) kit for the 7.62X54R for a nominal price.
Or, take a chance and try Wolf or similar soft points.
I consider .30-06, .303 Brit, 8X57, and 7.7 Jap in similar class. The rifles do differ greatly.