I clean the screws off real good and do not use any form of loctite. I use Leupold rings and bases and they use a torx T15 bit, so I have this little torque wrench to use...
http://www.cabelas.com/cabelas/en/te...box.jsp.form23
It is not fancy, only torques to one setting, but its perfect for mounting optics on guns. If you really wanted to use loctite, I could see using it on the base screws, because you can not tighten those once the scope is on and there is no need to adjust the base. But I would not put them on the ring screws because further adjustment might be necessary and you can access the screws easy enough to torque down again if necessary for some odd reason. I do recommend using some kind of torque wrench. People will say oh, you can just snug them up, well the first time you strip out the threading on your rifle base holes and have to get them retapped, you will wonder why you didn't spend the 30-50 bucks on the wonderful tool in the first place.