I have the fancy Sinclair micrometer that ran me about $200. But recently I saw that they have a new tool made by Insize that should do the job for $50. Here it is.
I have the neck sorter and it's great for segregating cases based on how much variation in wall thickness each case has, but it won't give you a thickness number.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pete H.</div><div class="ubbcode-body">How useful are the numbers obtained using the blades on my Starrett calipers? </div></div>
I was never able to get reliable numbers by trying to stick the points of the blades into the neck. I guess it's better than nothing, but calipers aren't made for that kind of work.
I think there are actually two main type of neck thickness measuring devices.
One that is used for brass sorting and culling. It allows you to rotate the case all the way around so that you can measure the difference between the high and low spots. I use a Redding for this purpose, it works great. This will give you a number but it is approximate i.e. +/- about 0.5 thousands.
The other is micrometer based device with a ball on the other end. This is used to get an accurate reading on the neck thickness but only on the specific spot on the neck that you place it on. I use a digital Mitutoyo which is very accurate and can measure down to 0.0005” but they are expensive. You use this to trouble shoot or confirm you neck thickness after turning.
