I just purchased a Remington 700 XCR Rocky Mountain Elk Foundation edition in .300 WSM and put a Nikon Buckmasters 3 x 9 on it. I need some help/input!!

...long story short, I cannot get it to shoot well! I have put 44 shells through it. I have it in a sight vise, and after the first box of 20 shellsI even got a hydraulic trigger release, then came back and shot the other box on a different day (new Federal Fusions) and a few Federal Premiums,first box 165 and second batch180 grain. I know that the scope/gun is being held dead on when firing (anchored & strapped into vise, and now with hydraulic release). I allow the barrel to cool between shots. I can manage to get 2 shots within 1 to1 1/2 inches... I think it's going good... then it will throw the nextshot off several inches (at 100 yards). The scope is securely anchored down as well (all screws & mounts). I did check the "float" of the barrel by sliding an index card b/t barrel & stock, and it will slide between. I was using bungee cords to anchor the gun tightly at two points: (1) downover the barrel at the forearm area, and (2) also at the rear stock where the "cheekpiece rise" is, and I don't know if that would affect it(??). Thanks in advance for the input!