I'm not intimatly familiar with the Alcione, but I do have a Veloce. Can't really say why you don't get a fire on the second shot on occasion. Are you sure you have it firmly against your shoulder each time. I suspect that the Alcione has inertal set trigger and may not reset if you don't have it firmly against your shoulder. My Veloce usually resets without a shell fireing, but it does indeed have an inerta block in the fireing mechanism.
Why the small indent in the uppr shell unfired primer when having only fired the bottom barrel? Fireing pins on most O/Us aren't spring loaded, they just float in the standing breach. When you fire the bottom barrel the gun recoils and the upper fireing pin responds to Newtons law. A body at rest tends to stay at rest. As the gun fires and recoils the upper fireing pin stays put in relationship to the universe but the gun with the shell in the upper barrel recoils rearward with enough force to allow the fireing pin to protrude and hit the primer hard enough to put just a tad bit of a mark in it. Not nearly enough to fire the shell, but definatly enough to leave a mark many times. Usually the heavier the load and the looser you have the gun mounted on your shoulder the greater the free recoil the gun has and the more likley you will be to get a mark on the unfired primer. Obviously if you go agead and fire the second shot you would have never known this! I wonder how many folks actually fire an O/U only one time when two shells are in it? I bet not very many?
BP
Why the small indent in the uppr shell unfired primer when having only fired the bottom barrel? Fireing pins on most O/Us aren't spring loaded, they just float in the standing breach. When you fire the bottom barrel the gun recoils and the upper fireing pin responds to Newtons law. A body at rest tends to stay at rest. As the gun fires and recoils the upper fireing pin stays put in relationship to the universe but the gun with the shell in the upper barrel recoils rearward with enough force to allow the fireing pin to protrude and hit the primer hard enough to put just a tad bit of a mark in it. Not nearly enough to fire the shell, but definatly enough to leave a mark many times. Usually the heavier the load and the looser you have the gun mounted on your shoulder the greater the free recoil the gun has and the more likley you will be to get a mark on the unfired primer. Obviously if you go agead and fire the second shot you would have never known this! I wonder how many folks actually fire an O/U only one time when two shells are in it? I bet not very many?
BP