Fortunately revolvers have forcing cones and one is not able to load .44 magnum in a .44 special revolver, same as .357 into a .38. While the reverse is true for specials into magnums that is not true of the Mk19. That ammunition is arrives belted. Even loading a round only separates a link from the next without removing the link from the case unlike MGs or autocannon. One is not able to load regular 40mm for the M203/M320/M79 into a Mk19 and get same to fire.