I have used Loc-It (blue) on all my scope base and ring screws for many years. It makes the threads "sticky" so vibration won't loosen them, but they are removable.
IMO it isn't really necessary to torque screws down REALLY tight. As long as all play is removed and they don't come loose, tight is tight.
As to your question about overtightening a synth, stock - even the strongest plastic can bend and/or warp under enough pressure.

yes, but can you over-tighten the lugs by hand with a screwdriver???

Yes indeed you can. I usually tighten them until they snug up, then another one-quarter turn.

Lot's of good possible solutions have been suggested. I can only speak for my Z5.

I had a similar issue and found I wash pushing the 250"s too fast. I went with a 300 gn. bullet, Harvester Short Blacks and 110 of T7.

This combo produced 1.5" groups at 100 meters from the lead sled.

Try slowing things down and as a previous poster suggested.

thanks semi (and the rest of the responders to this point).

can anyone explain why tightening to much is detrimental. I'm guessing that it does not allow the barrel to oscillate (sp) correctly during the shot or something but really have no idea and did not previously know that it was possiblef for them to be to tight....should I use loc tite (blue bottle)on the lugs??

how about the torque wrench idea for precise tightening.

I know right now the lugs are as tight as i can possibly get them by had with a screwdriver..so probably not right

thanks again all
hb

There is two reasons. In the plastic stock it can crush and distort some of the supports. Also it creates tension and changes the vibration [whip] of the barrel and so the bullet exits the barrel at different points of the vibration which causes it to be pointed a bit different.
The stock to action screws should be set at 28 inch pounds .

I have a synthetic stock Omega (older stainless one before the Z-7 came on the scene). It was a tack driver for about 50 shots then everything went to s%&t (crap). I believe it is the stock to action fit. It needs to be bedded to fix it but I have other rifles that are better out of the box so I have not addressed the Omega. It went from being my favorite to becoming my least favorite. Personally I am done with T/C rifles. The front lug is screwed on my rifle and with the screw tight the lug still moves from side to side. Not impressive for the cost of the rifle. You might check both of those items on your rifle.

If you are in a hurry and cannot bed the rifle before a hunt. You might try checking the barrel to stock and see if it touches on one side and not the other. If your barrel touches you can just put some shims under the front lug to space the barrel up and that might get you out of trouble for a short time at least enough to do your hunt.

Seems that cutting the screw shorter would fix this issue.

thanks again everyone for the replies...I'll let you know what happens. Looks like I'll shoot it tomorrow or Friday and then go hunting (assuming that the accuracy problem is corrected) on fri or Sat. Shouldn't need much time to find a fat doe in the wide open around here....just need a gun that I can use with confidence when pulling the trigger. take care all