Brown's Precision KS stock barrel channel?

[5RWill]

So long story short I'm on a mission to rebarrel our 700 KS custom in 300wby to 7PRC. I have a #4 wilson carbon on order. #4 sporter contour – 1.200″ – 3″ straight shank, tapering to .685″ at 26″. I for the life of me cannot find up to what size barrel the stock can accommodate, looking at it, I'm pretty sure I will have to open up the barrel channel. Does anyone know in particular? I messaged Brown's precision as well, though dunno if I'll get a response.