Originally Posted by 1stmar
The presumption is, it sizes from the inside where a bushing sizes from the outside and will be much more influential on neck tension due to brass thickness. I have nothing to substantiate this, just theory.
You and I don't but plenty of people do, and the presumption is correct.
It's not just neck tension either. Expander plugs being pulled out of unsupported necks also tend to pull the neck offline. The collet doesn't pull the neck off-center, which helps make more concentric ammo.
Still happily answering to the call-sign Peetza.
The problem, as you so eloquently put it, is choice.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.