I can't say who did manufacture the scope, but Winchester always took great care to ensure that all products manufactured by them were marked as such. If it doesn't have the Winchester name and address marking on it, it's not a Winchester.
It looks like one of the 8 X scopes that were available from Winchester as an option on early Model 75 target rifles. Did Winchester manufacture them? I don't know. Maybe they didn't, and that's why the Winchester name is not on them. But they were sold by Winchester.
By the time the Model 75 was introduced in 1938, Winchester had already ceased manufacturing scopes. I want to say this was in the late 1920's or early 1930's, but I'm not certain of the exact year. In fact, the equipment was bought by Lyman (at Winchester's request). As such, the early Lyman scopes were, in effect, nothing more than the old Winchester scopes with Lyman's name on them.
Still, though, if it doesn't say "Winchester" on it, it's not a Winchester.
The "X-8" mark has a familiar ring to it, though. I know I've seen it somewhere. Time to dig out the references...
Check out your reference books. But as I stated above, you will find that Winchester sold the 8X scope as an option on the early Model 75 target rifles. Nick Stroebel mentions this in his book "Old Gun Sights and Gun Scopes". Also, there are old Winchester ads for the Model 75 target rifle that picture this scope. In the ads it is referred to as the "Winchester 8X scope". It was a $9.50 option on the Model 75.
I tried to post this earlier, but there seemed to have been something wrong with my connection to the 'net. All is well now, though, so...
Tom you are correct, and I must correct myself. As soon as I was able, I checked my copy of Stroebel's book and there it was: In 1939 Winchester introduced an 8X scope specifically for its Model 75 Targer Rifle. This scope tube is unmarked except for a "8X" on the objective bell and has a "Japanned Brass" tube that gives a greenish-black color to the tube. The stamped sheet metal mounts may or may not be marked "Winchester".
It's still not entirely clear to me just who made these scopes, as in a preceeding paragraph he states: The A5 remained in production until 1928, when Winchester sold its entire telescopic sight business to the Lyman Gunsight company.
And in the chapter dealing with Lyman: The company's first venture into the telescopic sight business began in 1928 with the purchase of all tooling and manufacturing rights to the Winchestar Repeating Arms Company's A5 rifle telescope.
So, I'm still wondering about exactly who it was, Winchester or Lyman, that made these scopes. Did Wincheser re-tool for this, or did they simply have Lyman produce them? And does it really matter?
Either way, to give an answer to 45 Auto's second question, a bit further on he states that these scopes were available from 1939 until about 1944 or 45, and the value ranges between $200 and $400.