concentricity

not sure how many thousands of times this has been discussed but i couldn't find it in the piece of shit search feature. how many of you guys check concentricity of your case and the runout of your loaded round? what effects and at what run out do you see the effects or does it really matter.

I have just watched the redding advanced hand loading video. They had a Redding case neck gauge and it looked like a Sinclair concentricity gauge. MY question are booth necessary? I could be wrong because i don't know but it looks like the concentricity gauge will do the same thing the case neck...

I currently use the Redding competition seater die, but I currently do not have any gages to measure runout. I have had my eye on the Hornady Ammunition Concentricity Gage, but I called Hornady yesterday and they said it will not be released until July, 2009. It is the only gage I have seen...