Neck tension is perhaps more about mathematics than anything else.
To establish a calculated neck tension for hunting purposes (it's a little more involved for competition shooting) there are three "tools" that come to mind.
1. Bushing type neck sizing die (Redding is a common source)
2. Range of bushings to provide the desired results
3. Neck sizing mandrel (for neck interior sizing and shaping)
4. Neck turning device
5. Neck wall thickness gauge
Getting the neck wall thickness uniform over its entire circumference is pretty simple. First I size the brass, then run the inside neck sizing mandrel to round out the neck. I put the brass on the Neck turning mandrel and adjust the blade to barely touch the brass. I turn it, increasing the depth of the cut each time, until the entire neck surface shows that it's contacted the cutter. Then I check it with the neck wall thickness gauge to make sure it's concentric within .0005+/_
I don't get obsessive about neck tension for hunting loads, except to make sure the tension is evenly distributed over the circumference of the bullet. I leave the more detailed neck tension processes for competition shooting.