Loan Harvey,
As noted this is a 303 Savage, not .303 British. The good part is it takes .308 bullets not .311/2 bullets like the .303 British. They were, however, originally loaded with .311 bullets from the factory. It is one of the first "true" smokeless powder cartridges here in the U.S. It predates the Winchester 30-30 (then known as the .30 WCF) by one year. And, it had way better performance. It fell into oblivion after the U.S. invented the 30-06. The chambering was common from the beginning of the Savage model 1893/1895/1899/99 up until the early 1920's when the .300 Savage superseded it. For some more good info on these, here's a good website:
Redirect. According to that site, your rifle was made in 1921.
This round, although almost completely obscure now, marked the beginning of high performance ballistics here in the U.S. And the venerable/vaunted Savage 99 has always played second fiddle to lesser guns (Win 94) due to marketing. But, they are solid no-nonsense shooters.
That said, Buffalo Arms up in Sandpoint, ID has everything you need to reload for these. Reasonable performance of these will outshine a .30-30, but do not expect to hit .308 Win performance. The rifle is a good strong action to work with, but does not take well to hot loads. Kept reasonable, reloading for these rifles can be rewarding. Load hot and you'll find it's not worth working with in these rifles.
