Screws on Bottom of 300 RUM

[NVHunter1]

Hi
I need some help please, I have been reloading 200 AB with 88 gr H1000 and getting great groups, sub moa. I noticed the other day it looked like the screws on the bottom of my rilfe were a little loose. I tightened them up to 40 inch pounds and went out and shot this morning. I was horrified on what I saw. 200 yards right on the money, 400 yard group elevation perfect but 6" to the right, 600yards - elevation fine but 14" to the right. Can changing the torque on the 2 screws on the bottom on the rifle do this??? I shoot a Winchester Mod 70 Post 64 300 RUM. I was getting good groups before I changed the torque on those screws. Saddly I dont know what the torque was before I changed it but I can tell you they were preaty loose. I checked all other scope and mounting hardware and all good with Wheeler torque guage. Any help would be appreciatedlightbulb

 

[lamiglas]

what was the wind like?

 

[NVHunter1]

No Wind, very solid rest

 

[lamiglas]

I would not think the screws could do this. changing your torque setting can affect how your gun shoots but if it was dead on it 200 yards I don't think that would make your gun shoot to the right all the sudden out past a certain yardage? sometimes even when there appears to be no wind there's mirage and other things going on down range at extended ranges?