We got 28" (Their longest without extra charge.) 10 twist for about any bullet we cared to try, THREE groove.
My more experienced friend had signs that the three groove barrel would last longer than more conventional six groove.
I don't remember the profile number, something close to the factory varmint so we wouldn't have to enlarge the barrel channel in the stock.
Thank you! I also have the factory varmint barrel and will do the same.
Russellc