The 270 has the same ballistics with a 150 gr bullet as the 300 does with a 180 gr bullet.
Um I am not sure how you came up with this but at 400 yards(the distance you shot) the 300 win using the same bullet but in 180gr vs .270 in 150 gr ballistics (approx.). 150 gr .277 is travelling 600 FPS slower, has 1000 less Foot lbs of energy & 6"in drop. That ain't what ya call basically the same!!