Neck turning 284

[JayHHI6818]

Having an issue with bullet not going into some cases after they are fired. Necked up Lapua 6.5x284 Brass.
.317 chamber, loaded cartridge is .312, fired case .316
Definitely have a donut but I’m seating bullets above it. Very light skim on the necks. How’s the cut into the shoulder look?

 

[ngb1787]

Neck bushing may be too tight and u have spring back,

 

[mikecr]

The cut onto shoulders is extreme excess. I take it also that these were turned after firing instead of as new.
You could have turned the necks at 26cal, before up sizing. With this, you could have mitigated some of the donut that upsizing would immediately produce.
But with so much clearance already, I would not thin necks to increase clearance even further.

With chamber already chosen, and necking up brass already chosen, you might ream donuts.
I don't like reaming personally, so I would just never seat bullet bearing into, nor size, donut area.
That bullets won't drop through fired necks, resting at donuts: it doesn't matter.
Better Neck-shoulder turning: