Greetings, Java Man,
Your 1-48" Orion 58 caliber barrel is very, very interesting. I was not aware that Orion used the 1-48" rifling twist in any calibers other than 32, 36, and 40, and optional 45 caliber. The 1-72 was used for the 45 caliber and larger according to their advertising.
The Hawken popularity was at its zenith in the 1980's, and the rifling twist in the originals was 1-48" It would not surprise me if Mr. Cunnungham did a special run of barrels with a 1-48' rifling twist to capitalize on the Hawken rebirth of that time.
About the same time, Golden Age offered a special limited run of barrels made from soft iron with 7 groove rifling, 1-48" rifling. If I remember correct, it was offered in only one caliber and one size across the flats.
GA would not reveal the maker, only that it was made by one of the leading barrel makers in the country. I always thought the barrel maker was Bill Large, but would not be surprised if it was Jerry Cunningham.
Anyway, as I said your barrel is very interesting, and wish I had more background information on it.
Best regards and good shooting,
John L. Hinnant
If you are not an NRA Member, why not? I am carrying your load.