Truing is an attempt to locate every thing mechanical in the same exact plane/axis so theres no easy way for the action to deviate from those positions when firing, you cant expect a shot to go as straight and true as possible to each subsequent shot if everything in your action is wobbly and crooked.
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I wouldnt bother trying to true up the ruger. A good barrel is 90% of a rifles accuracy, truing is an attempt to make up that remaining percentages. Hell these days Im not sure I would bother truing up anything. Easier to buy something thats already true and the ruger should be fairly good.