7 saum - donuts

[Ginga]

Hi, I have a custom 7 saum and after 3 firings the Norma brass develops donuts. A hot load will do it in 2 firings.

Am i faced with just using an inside neck cutting tool to remove the excess brass?

Seems weird as I don't see this in other calibres.

Thanks

 

[Mikecr]

By manufacture cases taper in thickness from webs all the way to mouths. Without turning or reaming there is always some bit of donut. This grows with either necking up a cal, or heavy FL sizing to move brass into necks.

 

[ShtrRdy]

Can someone explain how an inside neck turning/reaming tool works? How does it only remove what shouldn't be there?

 

[Mikecr]

Neck reaming doesn't work well as it doesn't just remove what shouldn't be there.
You're better off to have a better plan..