My question is especially about current-production Ruger and S&W 10mm revolvers. Can they be made to headspace using the moon-clip and therefore accept a roll crip? I believe they can, and so then can the cartridges be roll-crimped? If I recall correctly, I've seen the Ruger loaded and fired without moonclips, which suggests it was headspacing on the case mouth. But I don't think it could do this with .40 S&W, and therefore it must headspace 40 using the moonclip. If that can be done, can either of these cartridges also be roll-crimped? One problem I suppose is that .400 bullets are unlikely to feature a crimp groove or cannelure.