I had the some problem with my Model 16 Weather Warrior -- until I discovered that the rear screw is the trigger guard screw and anchors into the plastic of the stock and not the action. It took less than 10 inch-lb torque to strip those plastic threads. Most of the on-line references, including those from Savage, did not alert me to this. I found out only after discovering the problem and digging deeper.
Your stock might be similar and it is worth checking.
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