Sure, if a guy is chasing BC. But a 140 gr .277 NAB beats a 140 gr. 284 NAB in that department.
Both still Accubombs.
In the worst case scenario, with low ambient temp, and at sea level, the 7mm will actually have a better BC per the Berger twist calc. Factory .270 Win rifles are twisted too slow to stabilize the 140 NAB under those conditions. At 25 deg. F., you'd need to shoot at 3900 feet of elevation with the .270 to get full stability. The .280 can do the same at sea level.
The .270 Baby Magnum is an awesome cartridge. I still have a soft spot for it, but it has limitations based on factory twist rates. As do the .280 and .280AI with 1-in-9 barrels, but they still have an edge on the .270 if splitting hairs.
