Dug up an oldy!
Finally a new guy that figured out how to use the search function.
Sorry, I can't tell you who made your shotgun, but I can give you some general information.
Navy Arms is an importer that has mainly dealt in replica arms, and kind of claims to have started the whole cowboy shooting thing.
The markings on your shotgun would translate to:
CAM 76 = 76 mm chamber = 3" chamber
the "star" and "star star star" or "*", "***" would be the choke markings, most likely indicating full * and improved cylinder *** .
The 18 4 would be the bore diameter, 18.4 mm = 0.7244". Most manufacturers are in the mid to upper 0.72_ range. There is some variation here as well as in choke diameter, nobody makes them quite the same (any gauges or charts that say a diameter of .xxx is a ___ choke are generalizations, or strictly for one brand). Choke is a function of the amount of constriction of the muzzle relative to the actual bore diameter. With manufacturers today embracing overboring, backboring, triboring, etc. the variation in bore and choke dimensions is probably wider now than ever.
I think the line you listed as "KG1 460" is some type of proof stamping for the amount of pressure the barrels are rated at, but I am not sure that you got it right. If that is KG 1460 meaning 1460 kilograms per sq. cm., it would be at over 20,700 psi , which sounds right, most 12 guage loads are around 10,000 psi.with some heavy loads around 12,000. I'm not real up on Italian proof stamping.
"Acciaio Vickers" is Vickers Steel.
"Cannes Cromate" literally translates as chromate canes, or as we would say chromed barrels.
Vickers once was one of the greatest companies in the world. Started in 1826 as a simple foundry, they grew from casting church bells to aerospace manufacturing and everything in between. They made the first submarine for the Royal Navy, planes, trains, and automobiles, tools, arms, electronics etc. The British government started to nationalize industries in the 50's and 60's. Parts of the company were stripped off, but I think Vickers Steel hung in till the mid 80's before being absorbed into British Steel, and the only part of this once great company still using the name Vickers is a division of Eaton Hydraulics.
hope I didn't bore you too much,
bergie