I've just finished forming some 6.5mm SAUM cases from 300 Norma SAUM.

First of all, I necked down the 300 SAUM cases in my Hornady 7mm SAUM FL die, without the expander, and no doughnut formed. Incidently, I checked runout and it was sitting around .001 - .002, so thumbs up on the Hornady die.

Then I ran those newly formed cases through my Redding 'S' Type neck die, first with a .298 Wilson bushing, then switched over to my .292 Wilson bushing for the final sizing as I understand necking down in greater than .005 increments can cause excessive runout.

Well, hey first thing I noticed was no doughnut formed and necks still have .001 - .002 runout.

So, why has this happened? I am curious as just about everyone who has been forming 6.5mm SAUM from .300 SAUM reports a doughnut forming...

OR ....

is this because they are forming their cases by entirely using their 'S' type neck die and changing the bushings. I haven't experimented with forming my cases this way, just the process described above as it works very well.