Do a couple things (after checking all your scope mounting screws)...
Fire a factory round and take the fired case and rotate it 90º and try to put it back in. That would show if you had a oval (out-of-round) chamber.
Then if that's okay, take it to a gunsmith and have him check the headspace. Shouldn't take long as he should have the headspace gauges.
Check the torque on the action receiver screws to the factory spec.
If the scope mounting screws are tight and the chamber is good and the stock receiver bolts are the correct torque, it should shoot.
140 gr bullets should shoot fine in that rifle. That's the normal weight.
And I hope you have a solid rest (bench using sandbags or similar) and are squeezing the trigger!