In my posting above I give the case a quick 360 degree turn in my neck thickness gauge "FIRST". This tells me a great deal about the case and what I will do to it during this neck sorting. Your .0015 difference is great, BUT with a off the shelf factory rifle neck turning may not show any difference in group size.
Much of what benchrest shooters do filters down to us, BUT 99% of us do not have custom rifles with snug tight neck chambers and with factory rifles all this case prep can be over kill and not needed.
Many of the FTR shooters at AccurateShooter.com just buy Lapua brass and do nothing but posibly weight sort these cases.
So again if you buy good quality brass like Lapua and are not a benchrest shooter trying to shoot bughole groups then nothing needs done to the brass. On the flip side of this if you buy Winchester brass to save money then more sorting and case prep needs to be done.
So do yourself a big favor and buy a cheaper neck gauge like I have above and forget ball mikes or using your vernier calipers. One twist of the case with this gauge will tell you a great deal about the brass you are reloading. This same neck gauge and a runout gauge helps when setting up your resizing dies for the least amount of neck runout. It doesn't do you any good to neck turn brass when the necks have excessive runout.
Redding Case Neck Gage w/ Indicator
http://www.sinclairintl.com/reloading-equipment/measuring-tools/case-gauges-headspace-tools/redding-case-neck-gage-w-indicator-prod39927.aspx
SINCLAIR CASE NECK SORTING TOOL
http://www.sinclairintl.com/reloading-equipment/measuring-tools/case-gauges-headspace-tools/sinclair-case-neck-sorting-tool-prod36959.aspx