I'm running a Bighorn TL2 kinda, (pre-Bighorn
Goddard action) Chanlynn pre-fit 6BR same as Kevin, my reamer. Disadvantages and advantages to both. The spring ejector can and will dent the mouth of the case on extraction. My Kelblys with the mechanical ejector does not but! The mechanical ejector system takes some getting use to. Soft stroke it, and the BR case can flip. Run it hard and no problem. On my Eliseo BR I kept shortening the ejector spring till it didn't dent the case mouth. I'm running the Primal Rights kits for mine by the way. Love me my BR!
The nucleus works just as you describe the Kelbly. Run it hard and it tosses them out. Soft stroke and it typically sits in the action.