Stock Ruger is most likley 1 - 10 ish , the standard twists depending on manufacturer are beween 9 and 11 . depending on the twist the best bullets that will fly will be in the 90 - 105 gr range . There is also caliber specific info here , http://www.6mmbr.com/243Win.html , forgot about it last time .

Hoser is just delicate and will see the light sooner or later and build a 7 .