111 LRH Action screws

Ok so last week I took the .300 win mag out for some long range shots. I've been getting some weird accuracy out of it lately. Groups haven't been super tight or anything. So I'm shooting at 500 yards at a 12" inch plate and I shot at it like 20 times and only hit it twice! I was high and low and left and right. Tried to make some adjustments and still getting the same weird results. So I'm looking over my gun today. Checking my scope, scope mounts and everything to make sure it's all intact. Then I check the action screws and they are barley screwed in! Half a turn to loosen them and they were off the threads.

Could this be effing up my accuracy by that much? And what poundage should I be torquing the screws to?

39 in/lb... FAT wrench was the best thing I have purchased yet!