Bought just such a barrel from Track of the Wolf in 2019. Searched all over before I got it and even then it took a while. Their website set up so you could ask for an email if/when it ever came back in-stock. After about a year or so they sent me an email saying they got it back in-stock. Ordered it that day!
Dropped right in to my Cabelas INvestarm stock. Shoots round balls extremely well even with HEAVY loads of 777. It is a 1 in 70, 54 Caliber.
I see, however, you're wanting a fast twist. I think they have those, too.
Track of the Wolf, Inc.
18308 Joplin Street North West
Elk River, MN 55330-1773
Phone: 763-633-2500
Fax: 763-633-2550
Website:
www.trackofthewolf.com