What period is this rifle from? I've never heard of it before.

The Ross was patented in 1905 and was well-regarded as a accurate rifle. The Canadians took it to WWI, where they found two major defects not previously encountered (gee, no one tested it under fire (no war to do that with) and living day after day in muck).

1. The action did not like mud. Neither did the magazine.

2. It was possible to take the bolt apart and put it together again - wrong. It would go back in, and you could shoot it - but it would fly right out of the action and into the firers forehead.

Not good. So the Canadians dropped the rifle for service use and used the SMLE. They did keep them around for snipers.

Oddly enough, I have a Ross bayonet as well. Though not one as nice as this and without its scabbard/frog. A friend of mine showed it to me once and said that he'd found it in a barn on a farm where he'd worked. And that he'd been using it to cut brush. I shuddered, then asked if he'd sell it to me, since it did have some historical value. He just gave it to me since I valued it.
The Ross rifle is an interesting story. It was adopted at the insistence of Colonel Sam Hughes, who was Minister of Militia at the time. It was an excellent marksman's rifle, but dangerous to the user if it got fouled with mud or dirt. A lot of them were converted into sporterized versions between the wars. Another friend of mine owns one such.