I bought a Sinclair concentricity gauge years ago and it's nice to know that my necks are straight but what I found is using the Lee collet die keeps runout near zero. I bump the shoulders with a Redding body die then neck size with the Lee collet die. I'm sure any mandrel die will do the same. 
If I didn't have the money for the concentricity gauge I would just buy the Lee collet and not worry about runout.
				
			If I didn't have the money for the concentricity gauge I would just buy the Lee collet and not worry about runout.
 
	








 
 
		
