No sn data available.
Crescent Fire Arms, sometime between 1893 and 1932.
You will have to be more specific... there are a lot of firearms companies and manufacturers called "Keystone". Got a city/state where they operated? Anything?
NORIS appears to have been a firearms manufacturer in Spain who imported shotguns and rifles into the US during the 1960s.
The Savage Arms Company is an American manufacturer of firearms. One can purchase Savage firearms accessories directly from the manufacturer's website.
japan
There are many things that the company FN Hestal manufactures for a wide variety of customers. Some of the products they manufacture are firearms and accessories for firearms.
Ruger
The answer depends on what "best" means to you.
yes they did
70s
You must contact the maker.
Probably.