Hi All,
I would avoid the shoulder bones as they are heavy. Like all Hunting it's about bullet placement, and as for your groups .............................. well you shot them and you measured them, so you Know what it's doing
Having a couple of rifles chambered for the 270 Winchester cartridge I am well aware that they can shoot very well indeed.
A good barrel, accurate chambering and fittng to a true action. Then bedded into a true stock, there is no reason why the rifle and cartridge combination cannot provide superb accuracy with a compatable load just like any other well fitted rifle. One of my .270 rifles with the right loads is capable of 1/2 MOA accuracy, the other I have not had long enough to really check out. One rememberable shoot was at 600 yards and I shot a 6 shot group of just under 5". It was in a little club competition, 6 shots highest 5 scoring shots to count. I was shooting 130 grn Noser Ballistic tips over Reloader 19.