Re: what caliber
I shoot a 270 Win also, and what I am using is 140 Accubond, real glad with its results. No big upgrades on the rifle. Mod 70 Pre-64 Win, standard barrel, 22 inches, pillar bedding, free floating, worked on the trigger a little bit, and is releasing at 2 1/2 pounds. Shooting Sub MOA at 100 yards. The load I am using is Winchester brass, CCI primers, IMR 4831 powder - 56.5 grains, with 140grains Accubonds, muzzle velocity 2856 fps.
At 500 yards you have to dial in my rig 8.26 MOA, energy 1238(ft-lbs).
Deer die like lighting striked them.
Hope it helps.