OzFclass

Anyone had any experience with sako 308 cases. Have a clubmate who has been trying them.(originally bought as loaded ammo)Getting a pronounced groove around case head after 3 firings.
Cases have only been necked.

Possibly too tight on the neck bushing

Sako cases would be the same as any other cases. No-one serious necks sizes. The ring is probably the web expanding. I'm surprised they aren't tight to chamber yet after 3 firings. Tell him to full length size the cases for a 2 thou shoulder bump.