I would try R26 go with the Alliant data, it is a winner in my rifles. Just run it up to max and then start adjusting the bullet jump is all I needed to do for mine. The FC has a 1-8 twist I believe and is perfect for the 105s-108s not sure about the Sierras or the 115s in a 1-8 but will try them at some point. The 110-115s may be iffy.

That rifle deserves good brass, I would stock up on Lapua if I had it to do over again. Currently I have probably five different manufacturers brass and this doesn't help consistency. If I were smart which I am not I would scrap all the odds and ends and get Lapua.

"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