It's been interesting to see how the definition of "old scope" has changed as I've grown older. The scopes mentioned early in this thread still don't seem all that old to me--until I think about it some!
Among those I've hunted with are at least one brass-trimmed Weaver, a Noske 2.5x, a couple of Lyman Alaskans (not the Leupold reproductions but the original 2.5x), a Kollmorgen 4x, and a Hensoldt 4x from the 1950's. Right now I have on hand a Nickel Supra 4-10x and a Lyman 5A that are "looking for rifles."