Bring them both just snug, then tighten the h
ll out of them with an impact wrench.
Actually I have a method that seems to work even on Husqvarna 98 Mausers. I snug both a bit, then I tighten the rear guard screw very tight, then I tighten the lug screw very tight. Short of glassing the heck out of the action, this seems to work adequately. I also frequently tighten the screws on guns I get from out of this area with its dry climate, as they dry out over time.