chiappa 1887 shotgun

[Barbarossa]

I have a Chiappa 1887 shotguh and for the most part love it.It cycles smoothly and is beautifully finished inside and out.My only problem is the gun is loaded with a round in the chamber and the hammer  set on half cock when the hammer is set at full cock and fired the result is a misfire with a light firing pin dent on the primer.However if the gun is cycled normally with the hammer in the full cock position(without it being put in halfcock for carrying etc) the gun fires everytime.Can anyone give me a way to remedy this.I like the gun a lot and want to use it for hunting.