This is a solid brass, round nose projectile with a diameter slightly over .266″. These are loaded on a Citizen Swiss machine and the consistency is remarkable.
Note that there is a wide range of bore diameters found among rifles (and carbines) chambered in 6.5 Carcano. This projectile can be successfully loaded for all bore diameters with sufficient rifling. As with all proper loading practices: work your way up from a known, safe starting charge weight. When loading with monolithic bullets, it is common practice to begin load development using load data for the next heavier class of bullet as a frame of reference.