The Bullberry website says you can size the 25 BB in one step from full sized 30-30 brass. I've tried, and on some of my cases I get flat spot on the shoulder. No wrinkling, just flats, and it's not on all of them. I'm using once fired brass, and didn't think it should be a problem, but now I'm not so sure. Anybody have any experience with sizing the 25 BB?