I had 2 of those big Russian spam cans full of 7.62x54R military ammo (ordinary ball) in packets of salmon-colored paper tied up with string.  More than 400 rounds per can.

Exercise #1 was to see if they would all chamber in my M39 or SA-marked 91/30.  They would not all chamber. 

Exercise #2 was to pull about 250 bullets and measure diameters.  Very few less than .310".  But many were .311 a d .312.  Some were as large as .315.  Cartridge cases with the fat bullets would not chamber in either of my rifles.