The 10mm was born from the FBI's research after the Miami -Dade shooting in 1986 where agents went against determined and well armed bank robbers and died tragically as a result of the poor performance of the 9mm. The 10 MM was general issue for only a short time as recoil was difficult to manage and penetration excessive. If I were looking for a back up gun in the hunting field I would choose the 10 mm as it is balistically very similar to the 41 magnum revolver cartridge. In a gun meant for concealment I would easily opt for the 40 as it has far less recoil and penetration, holds more ammunition and has a smaller grip frame..