Try dropping the charge by 4-5 grains. It will make hardly any difference to velocities, lower pressures considerably and might just make your load very consistent accuracy wise. It's possible you are at the high end of the spec for bullet performance.
As mentioned above, when a load is that touchy, temperature and or just about anything else, like case weight can have a deleterious effect.
I had a similar problem with a 338 Win Mag. It was on a Rem 700 with a 26 inch bbl. It would shoot "red box" Federal 225 grain bullets into an inch or less all day. My hand loads, even though they were just slightly hotter would go all over the place, depending on conditions. Funny thing, at 100 yards the bullet holes were round. At 150 yards the holes were egg shaped (larger group), 200 yards, three foot pattern and the bullet holes looked like a profile of the bullet. There were 0 pressure signs.
I reduced the load by 5 full grains and all was touched by a magic wand. No more problems. I sold that rifle to a fellow that felt a rifle should have substantial recoil to be really effective. He still uses the mid range load and the rifle just keeps on performing, even though he abuses the hell out of it.
Don`t feel bad
