First, Winchester did not promote their 140gr at their factory velocity as having better SD/BC than the 7RM (which it did unless heavier .284 bullets were used which took away some capacity and velocity). They were promoting the 100gr loads, and that was considered marginal for anything bigger than deer/antelope at that time.
Second, Winchester shortened the barrel lengths, 26" should have been the mandatory for all .264WM chambered rifles. Shorten it, and you move into .270W territory with additional blast, recoil and powder consumption.
We are saying pretty much the same things, from different angles.
