LE Wilson FL Bushing Die or expanding mandrel ? Or both ?

[Gold13]

Fairly new reloader here

Looking for some advice on if I need a FL bushing die or not.

Am currently using a standard Redding FL sizing die with decapping rod removed and then a 21st century expanding mandrel to open my cases up to 1-2k neck tension. I get some ammo that touches on paper, and others that don’t. 2 might touch and 1 be off. I’m told it’s my neck tension and that expanding mandrels will have some spring back in the neck after running them through. (I’m annealing 300 WM Nosler brass with an AMP, btw)

i have been referred to a LE Wilson FL bushing die and to just forget the mandrel. My thought is that there will be spring back either way (FL bushing die or mandrel)

I have seen people post that they use both, some post saying that there’s no need for a mandrel unless prepping new brass or fixing bent/dinged case necks... I’m throughly confused and have a batch of Peterson 300 WM brass coming in and I’d like to not waste it all along with my rare H1000 trying to find the best process.
My process with Nosler brass is clearly not working.
Any help or opinions on this would be greatly appreciated.