As jeepkid asked, have you checked everything on your rifle first? I have a Winchester model 70 Super Shadow in .270 WSM. I couldn't get it to shoot better than 2-1/4" at 100 yards with any ammo I tried. I bought a Boyd's Laminated stock, pillar and glass bedded the action, free floated the barrel and now it's a sub MOA rifle. The stock was actually pushing on the right side of the barrel. Check all of that first or you will just be chasing your tail with ammo. Then follow all of the advice you've gotten about ammo.