I suspect that the Italian proof level my be the problem. It is likely the Italians consider 80 gr a service load and its proved to use that charge. The proof load for a 72 caliber using 180 grains of powder as a service load would be different I suspect. But I have no idea what the Italian proof laws are.
I suppose some research would give an idea of what the proof load is for this bore size.
IIRC historically the British had different loads for different classes of guns and a rifle would be proofed according to its "class". But I am not sure what the proof law was circa 1850.
If its stocked right 9-10 pounds will be OK hunting but will make shooting off the bench more "difficult" with 150-200 grains of powder.

Dan