Vashper, do you have any information on the cartridge with the 10.3 projectile in the 53/54 mm case? Bullet weights, velocity, etc.
It appears very similar to a wildcat I have called the 405 Grenadier, a .412 dia. bullet in an improved /blown out 7.62 or 9.3x54R case ( mine is built on a Siamese Mauser action with a Pac-Nor barrel )
