Hello Gary, welcome to the forum. It is a 1941 Mauser (byf) originally, the E/655 (eagle 655) is the proof marks. The 8,81 should be the bore measurement from land to land, although it could be the serial number. There should be a serial number at the front of the frame, might be 2 or a 4562, or any combination up to 9992.
Wal-Mart has Winchester 9mm that shoots nice in most guns.
Ed
Wal-Mart has Winchester 9mm that shoots nice in most guns.
Ed