If minutia is to be compared and to make it even more simple at least pick common weights (Nosler’s LRAB .277 150 grain has a G1 of 0.591 while the .284’s is 0.546)…
You are a walking commercial for the 27 Nosler, because that 150gr ABLR is designed to require the 1:8.5" twist of that cartridge. It can't be reliably used in a factory .270.
There are no magic bore diameters, but there are twist rates that allow better performance. The .270, in Winchester's ignorance, got the wrong twist and sucks if any sort of distance is on the agenda. Of course the fangirls can't hear this about their crush, but it's true.
