25-06 AI Neck Sizing Issue

When I neck size my 25-06 AI with a Redding Type S Busing Die I get a donut around the exterior of the neck – every time. The “dreaded donut” most think about is formed on the inside of the case neck at the shoulder neck junction as the brass flows forward during firing. My donut is formed on the exterior near the shoulder and caused by my Redding Type S Busing Die.

I was told by Redding (Chris Fox) that what I was seeing was an unsized portion of the neck. Redding’s solution is to use a Series Neck or Full Length die.

Is what they are saying is that I should use a neck or full length die and then from then on I could use my Body Die & Type S Bushing die or until the donut appears again?

It sounds to me like you have a generous sized neck in your chamber ; are you necking the brass down more than necessary to hold a bullet correctly ?
Do your cases chamber after neck sizing ?

I think the case prep process I went like this:
- Uniformed the primer pocket
- Deburred the flash hole
- FL sized
- Loaded and fire formed
- Deprimed and cleaned
- Trimmed to length
- Turned the necks

This is when I tried to size the necks with the Type SBushing Die and got the donut at the bottom of the neck

No – I didn’t try to chamber after neck sizing.

I have been using a Lee Collet die to size the necks butwould like to use the Redding Type S

Can you can slip a bullet fully down the neck of a fired case ? Does it appear to be very loose when doing so ?
Have you measured the neck OD of a fired case to get an idea of your chamber's neck size ?
Have you tried a larger bushing ?
Just ideas for things to maybe check -- not trying to be critical.
I guess my thought without knowing more specifics about the rifle is if the sized cases chamber and the neck is free maybe don't worry about it ?

I often see a "donut" on the outside of my necks when using the bushing die depending on how far I need to size the neck down.

BTW : Many consider the collet die a good way to go and that they give very good concentricity.