I am new to the 6 PPC as of this spring. I shoot VV133 & Barts Ultra 68's. I am told there are various "nodes" for this load. I was guided toward 28.7 gr of VV & it seems to shoot pretty well. Are there other "nodes"? I assume these represent MV's that I reach with this load. And,,,,,what is a "node"? As alwsys, thanks/ Chaz