Re: 300 WSM Seating Depth / Coal
I have loaded the 300WSM for about ten years and I have found that with most bullets seating close to the lands is not always necessary. With my two guns(Winchester Model 70, Ruger Mark II) I have shot many different bullets from Sierra Match, Nosler Accubonds, Nosler BTs, Nolser Partitions, Berger VLD's, Barnes TTSX, and Barnes TSX's, and the only bullets that I shoot close to the land was the Bergers.
Because the Winchester allowed me to get the Berger up close, I was able to and they shot well. However, my Mark II with a shorter mag also shot the Barnes TTSX's very well .050 to .070 off the lands. The Nosler Accubonds, and Partitions shot great in the Winchester without getting them close.
I would try the Bt's at the length that they fit the mag and see what happens. You may find that they shoot great as I did with the Nosler Partitions in my Model 70.