Rimmed Center Fire I.D. Help Please

Hi Fellas I have this rimmed round that is of the same style as a Nagant and 8 mm Pieper with its bullet contained within its case. This unknown to me round appears to have the same bullet dia as the Pieper. My 8 Pieper has a REM-UMC headstamp and its over all lengh is 40.93 mm., with a Rim Dia of 10.04. The round i am trying to ID has an overall length of 50.51 mm. Rim Dia 10.11mm., and is headstamped FN at top and 2 Stars at the bottom.

Thanks in advance, joe

7.65x50R Pieper rifle

Thanks Pete