Partial neck sizing help please

[Yotewhacker]

I purchased a Redding bushing neck sizing die to use with my new 243 win LW barrel, and several different size bushings. After shooting up some new brass I am experimenting with the neck sizer, and would like to try leaving some of the neck unsized to better support the case in the chamber. The neck bushing can be set up to float up and down so that only the desired amount of the neck is sized.

My question is for you guys that may have experience with this method, how much of the neck do you normally size back to dimension?
TIA for any help. ;D

[GaCop]

I usually size at least 2/3 of the neck.

[Yotewhacker]

I usually size at least 2/3 of the neck.

Sound sensible to me, so I will start there...thanks.