Try using leadshot bags instead of sandbags less movement.Also try 57gr.IMR 4831 with the 130gr bullet in the .270.It's been my standard load for 30 years.Running at about 3000fps.Make sure only the fore end of the rifle is touching the rest and have a support bag under the butt stock.Both elbows should also be grounded comfortably on the bench.Try for consistancy when shooting and your groups will tighted.Always wear ear protection to prevent hearing loss and flinching........Hope this helps..........Harold