The neck OD using the collet die should have been listed as 0.3305" not 0.3005". A typo. Meaning I get 0.0005" to 0.001" of neck tension using the Lee Collet Die. Full length indicates around 0.002" neck tension.
Made another discovery this morning. While rechecking the above data, I picked-up a bullet and measured it. The dial caliper indicated 0.305". That's not good. Checked the bullet using another caliper and it read 0.308". While the measurements above may not be accurate, the relative differences should be accurate. Guess I need to check all my calipers. I was making sure that the dial was zeroed before and after measurements.
Just to be sure, I checked some cases using the apparently actual caliper.
The OD of full-length resized cases was 0.334" to 0.335". The OD of loaded rounds was 0.337" to 0.338". Looks like a neck tension of about 0.003". That makes some sense.
Did not want to deprime cases to generate and measure collet sized cases; so I just measured the mandrel. It measured 0.306". So, the neck tension, has to be less that 0.002" on a loaded round. The rounds that I have unloaded were very easy to pull. Don't think there is much neck tension there. Polishing the mandrel to gain a 1000th or so is still a consideration. But, before I do that, I have one more test to do to verify in my mind that it is really a neck tension issue and not a powder and/or primer issue.