Sorry, so it's a 6.5x54 Mannlicher in a "Greek service" rifle sporterised. Have I understood your post?

If it is a .264 you're laughing. My William Evans Mannlicher also has a .264 bore and shoots .5 for 5 139 Lapua match HP's. With regular 160 RN and 140 BT it will group between 1MOA and 1.3MOA depending on the bullet and load.....not bad for something that was built before my father was even conceived !! LoL