Don't know what the original BC's were for the projectiles loaded into the Military M41 6.5x55, or the 7x57. However, I've found that the Hornady 140gr SP Interlock in 6.5mm, and the Hornady 139gr Sp Interlock in 7mm (both flat base projectiles), seem to regulate to the sights in each of the Mauser rifles chambered in these two calibers at 300m. This was as far as I tested as the range I shoot at maxes out at 300m. This was a long time ago, so I no longer have the load data etc.