Or what is it called? There was a guy on the web doing some neat stuff, explaining why match-grade loads work. Had to do with known harmonics of barrels and the time it takes for them to travel back and forth down the barrel. You find a velocity that allows your bulelt to exit inbetween one of these harmonic nodes and the barrel is at its stillest, most repeatable point. He had it all easy to figure using QuickLoad. Now I can't find it.
Anyone?

http://www.speakeasy.org/~cdlong/shooting

http://home.earthlink.net/~dannewberry/dannewberrysoptimalchargeweightloaddevelopment/

The first is from Chris Long, and the second is from Dan Newberry.

I believe the one you are looking for is the one from Chris Long.

Tim

Tuning for a good node is easily seen with a bench gun. You can start out with a low powder charge, shoot 3 rounds, then increase the load and shoot again at a different bull. You can watch where the bullets hit at a different place, but also watch them close up as you sneek up on the right load. You can also find one or two loads that work, one on the mild side and another at the top.