I would offer the opinion that the No.3 was a .375 Winchester and not a .375 H&H, unless it was aftermarket rechambered. Also, the 1V in .300 WM was a cataloged offering from about 1972 for about 6 years. they are not often found today and could be considered rare, especially the Liberty marked one.
There are a lot of No.1's rarer than this one!
