this may sound odd, but...
grab a gallon milk jug out of the fridge< anything heavy will work, that you can hold in your hand > put the rifle into your shooting shoulder, and grab the milk jug with the hand you would operate the bolt. lift up the jug until it passes the action of the rifle. wherever on your hand you find it compfortable to lift up on the bolt handle, in reference to it's position when lifting the milk jug, is where the bolt should be. shorten the stock until the bolt is in this position. This is to determine where the fulcrom of your arm is in relation to the bolt. you will automatically extend your arm to it's strongest position, when you lift the jug, conciquently, this point is also the most compfortable place to hold your arm when trying to get leverage on a rifle bolt. this works, try it. trigger pull is another concideration. i think this is more importaint,as accuracy will be aided by a compfortable trigger length of pull more than an easier place to operate the bolt.