My dies are RCBS dies, have worked ok in the RL 550 for years with brass. The expander die is the Dillon that goes with the powder charger. I tried a test with newer brass cases and 230 FMJ Win bullets. Upon chambering a round in my Kimber, the bullets sink consistently about .002. Lead 200 SWC bullets do not sink at all. Since I will only ever typically chamber a reload once, that is ok. With the steel cases, the Win 230 FMJs seem to sink noticeably more. I will keep experimenting when I have time.