Re: RCBS Precision Mic
I'm assuming this post was actually meant for Tom (Statjunk) but yeah, you got it. Tom, as Tackdriver said, your neck sized brass and an unsized case fired inthe same chamber should show the exact same headspace reading on one of these gages; you haven't touched anything there to change anything.
Not familiar with the RCBS videos, but the'd be a great source for the info on their tool. Certainly worth checking out!