Boat Tailed bullets do not show any real advantage until about 400 yards. Often Flat based bulelts show better accuracy than boat tailed ones and the boat tail can or seesm to be reasponible for some bullets of tradition make up shedding their jackets.
Now evey barrel let alone rifle is different so what one barrel in a particular calibre (note I said calibre and not cartridge
) likes may not be the same for the next barrel/rifle tried. Perhaps a better selection for the .270 would be the 140 grain bullet
and the 7.62 nato was dsigned around the 147 grn and .308 win adopted the 150 grn so?