For the Aspiring Gunsmith, this tool will prove its worth a thousand times over when testing mounts. I center point every set of rings i touch, and then I test lap them to see if they need lapping, if so then I lap them till they are true. I've yet to have a scope torqued improperly do to recoil, other than two piece bases.

http://www.brownells.com/gunsmith-to...s-prod833.aspx

Unfortunately two piece bases are just that, two pieces. There are many more chances for the two rings to not line up, so I tend to stear clear if the rifle has no common rail to mount them to. I'm not trying to pee on anyones good intentions, just placing some food for thought.

If there is a cut out on the top of a receiver that is larger than the cutout on the bottom, ie the ejection port vs the magazine cutout, when the rifle fires and the metal flex's all of the tension or shock will travel to the weakest side, which just so happens to be the ejection port. Well if we use two piece bases, then we are using the scope itself to stiffen the action of our rifle. By using a single common rail, or 1piece set up then we then place the shock into the rail instead of the scope. THis will help avoid scope damage, and make mounting scopes easier in general.