Re: Bullet seater is leaving a ring on the bullet???
Case necks have .001 ~ .002" of elastic deformation.
Stress is still proportional to strain.
Keep stretching the neck larger and plastic deformation starts.
During this phase, the stress is constant.
Why do you care?
Because the gun culture has some errors.
One is how the term "neck tension" is measured in change in diameter. Neck diameter change is only a valid indicator for tension for very small singular changes in neck size.
Tension is the tangential force of the hoop stress in the neck.
The force does not keep getting bigger with more change in diameter. After .002" it has no more force to give. It has reached the yield strength of the brass. Annealing makes the yield strength less, and so the change in neck diameter to reach the limit of elastic deformation is less, and so the neck tension force is less and so the bullet insertion force is less. But hard necks and twice the bullet insertion force probably does not explain beat up bullets.
The insertion force for the bullet is then proportional to: 1) the REAL neck tension, 2) the co efficient of friction between the bullet and the brass, 3) the circumference of the bullet, and any force needed to compress air or powder.
The correct amount to re size a neck is often .002", because you can't get any more tension than that, you can only get more eccentricity and work hardening.
There are a number of threads on SH about ring around the ogive or bullet is stuck in the seater die. These are often fixed by de burring the seater stem mouth. A sharp seater stem mouth can cut into a bullet with ordinary bullet insertion force.
I have been telling Forster to de burr their rough de burring cut on their seating stem mouths for 8 years, and they are still not doing it.
Another thing that can cause it is ball powder.
It has a very high bulk modulus [does not compress easily]
A compressed load of ball powder will beat up the bullet something awful. Compressed powder problems are associated with much more force at the press handle.