My current 7RM has a 23" barrel and I wouldn't want it any shorter. If building I would go 25" as a compromise. A 1 in 9 will be good for everything up to the 195 Berger but some of the Custom makers are producing 200 grain bullets so I would go 1 in 8 just in case I wanted to experiment. If in doubt get a 26" barrel and you can hack it down if it is too long for you.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli