When we could have these in the UK- in the good old days -, one of the shooters at my local club used the half-moon type clips on his Mk6 BUT only machined the cylinder up to the line of the clips. That way he could use the clips and when he could get .455 (usually Fiocchi stuff) he could use that because the inner part of the ejector that hadn't been machined down held the cases rearwards and would eject them too.