NdA: Check thorough this list, because many inspectors shared the same initials along the decades. I.e., SG in an oval marking on a 1918 Terni rifle will be a different person than SG in a circle on a 1898 Torino Rifle. 

These lists are NOT complete by any mean, they're just a first attempt at cracking the Inspector codes on Carcanos. 
Further research may change small elements, but most importantly more inspectors may pop up..