I agree with Dave. I have not noticed any difference in chambering from my Shilen to my Bartlein to my Rock Creek.
I don't care for gain twist but other guys do... I think it is one of those things that sounds like it may be a good idea but has no real relevance. JMO
All Rock Creeks are gain twist.
Eddie, My Rock Creeks are about 8yrs? old. They are not gain twist and are cut rifled.