Crow hunter,
The 139 Scenar doesn't have to be seated nearly as deeply as the 140 VLD, which is one of its advantages. But neither one would be a problem in a 6.5/.284 with a 3" magazine, and contrary to popular belief seating relatively skinny bullets a little deeper doesn't reduce case capacity enough to make any significant difference in velocity.
But I don't think RBO is considering the 6.5/.284 anyway. It was mentioned to illustrate the difference in case capacity between the .308 and .284 cases.
