Lead ?

[TexasMac]

When I shot it last (.376 bullet in a .376 groove diameter barrel) with a Walter's Wad at the base I got these lead rings. Time before that same loading but no rings. I suspected they might be because I'd left the bell on the case neck. I had done that because they chambered fine and I thought maybe they'd help center the full-lenght-sized cases in the chamber better that way.
Something in the bell remaining encouraged the rings because today I didn't get but two rings (in all three sessions there is no leading in the bore). This time I layed the bell back down with my sizer.

SgtDog,

I also bell the case lip to ensure the rear of the bullet is centered in the chamber, and have had not rings or problems. It's been my experience that lead rings are the result of a sharp transition step from chamber to bore along with exposed lead just in front of the case lip under the transition step. To eliminate the rings position the bullet so that a lube groove is just in front of the lip. When the bullet obturates the lube rather than lead will fill the transition step preventing lead rings. I hope that makes sense.

Wayne