I have some 6.5 284 Norma BRASS THAT HAS BEEN FIRED FIVE TIMES. I aneeled it on the fourth firing. I originally turned the necks when I got the brass. I thought I would trim the brass and it hasn't grown at all. I thought I would for good measure, go ahead and re-turn the necks. When I slid the mandrill in, it only went in a little ways, and then stopped. I had to really force it in there with great effort. At the bottom of my necks there is like a rim of brass. I think I have heard this called a donut, but I don't know why this is there or how it got there. It wasn't there when I originally turned the necks. Any help would be greatly appreciated.