The owners manual tells you the correct order to tighten the screws. If you do not tighten them in the correct order, you could potentially, and probibly will, open your groups up quiet a bit. I know a couple of time where people have blamed the poor acurracy of there rifles (4-6" @ 100 yards) on Ruger, when it turned out that they took the gun apart, they put it back together wrong.
I posted a request some time ago to get the proper torque values for M77 MKII's. I will post the information below. I wish I could remember who gave me the information though.
Charlie
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How to Torque M77 MKII For Increased Accuracy
The sequence and torques are:
1. The diagonal screw, torque to 50-90 inch-pounds.
2. The aft trigger guard screw, 30-50 inch pounds.
3. The forward trigger guard screw, also to 30-50 inch pounds.
The torque values will have an effect on barrel harmonics. Ruger uses the upper limits when assembling. But some experimenting may be helpful if you want to tweek the lst little bit of accuracy out of the rifle.
I use a slightly different sequence:
1. Forward trigger guard screw, just tight enough to hold the magazine well in place. Then close the magazine floorplate; this positions the trigger guard properly. Yes, it is possible to get the trigger guard positioned where the magazine floorplate won’t close!
2. Aft trigger guard screw. Tighten to hold the trigger guard firmly in place.
3. Then open the magazine floorplate, and use the torque sequence at the top of this post.
**Sometimes just adjusting the torque on the diagonal screw will make all the difference as far as group size. I usually do it in 5 in-lb increments. Just remember it's 35 in-lbs minimum and 90 in-lbs maximum on the diagonal screw; 30-50 on the trigger guard screws.