Recently came across a box of 7.62x54r, in a can, belted. The can is painted green (duh) with red letters that read 88-56. I'm assuming but the shape of the can this was for a vehicle mounted PK machine gun. So I set about the task of stripping them off the belt (these are for M-44 plinking), and notice the brass of every fifth round is brighter than the rest. All of the tips are painted yellow, but the brass is noticably different. Any thoughts? Tracer?