I am aware that specifically designed "riflings" of a barrel or tube improve accuracy of at least relatively short projectiles (or vice versa on the projectile, causing it to rotate), I guess by a sort of gyroscopic-type effect that keeps the projectile from tumbling. This is probably a stupid...
Does anyone know if there are any significant differences between ISO 6506: Part 1 Method for the Brinell hardness test for metallic materials and ASTM E10 - 07a Standard Test Method for Brinell Hardness of Metallic Materials?