What you need to do is buy some tools to measure your neck to actually see what is happening. The idea of using carbon from a match or markers is just asking for problems.
It is??? That's news to me, as i've been using a marker since the 60's without problems. I have no idea, how many folks i've taught to reload over the years, and that'show i also taught them to do it. I never had one come back with a problem of any kind from doing so...
If you can't "see what's happening" using a marker, then you need to have someone show you how touse that methodproperly too...
BTW, to the origional poster: almost without exception, you can't only "neck size" with a fl. sizer die. Allyour "really"doing, is sizeing the case "less" because you don't push it all the way into the die...If you really want to only neck size, you need to but another die...
DM