JOC also wrote about [don't remember which book] the spooky accuracy of some 200 grain bullet in his 30-06. Perhaps it was the Partition. I believe he was so enthralled with the tiny groups that he expended all his supply in 'group shooting'.
For what it's worth, JOC was a very big fan of the 30-06.
Just think what he may have accomplished in life with a .300 mag...
DF
He had a 300 Weatherby....
Being you mentioned it, I do remember that and seeing him in photos with Roy.
I don't remember .300 Wby articles by him, although there must have been some.
DF