Nothing really unusual, other than the receiver bridge. The rifle itself is clearly a MkII**, almost surely a Commercial.With the 30 1/2" barrel fitted to "short" wood precluding fitting a bayonet, only Commercial. All four variations of the Military MkII** fitted a bayonet. Only the first variant had "short" wood, but by using a long "sword bar" on the nosecap, a bayo clipped on. If there's no Factory-applied serial on the barrel just ahead of the receiver, I'd suspect a skilled gunsmith who was capable of milling/fitting/attaching a one-off base likely ordered a replacement barrel from Ross and then fitted it himself. Had Ross fitted it, the original Ross-applied serial would have been stamped on the new barrel, then a same-size "2" would have been stamped right below the serial. The rear sight is a CanTool Commercial; nothing unusual at all. It will be clear to anyone who has read sales literature from Ross that his Target rifles were normally sold without a rear sight, on the understanding that anyone interested enough to buy a dedicated target rifle would also have definite opinions as to just which sight he preferred. The "barrel replacement" offer is also in print.
The foresight hood was an option from Ross.The hood tips forward. With the one-piece topwood, the rifle would have been from the last 30% of production....original serial likely between 6,500 out to the end.
If you have either the patience or desire, you could either search this site under "Ross####" courtesy CanTom, or visit RossRifle.com and check out the Photo Album section and check out perhaps twenty sight variations on MkII**'s from my collection. My four variations of the Military MkII** are also shown.