Make them from .303 British.............Harold
X2. Until I was able to obtain some 7x57R brass that's what I used. It isn't perfect, basically the case comes up a little short, but it works fine and there's lots of that around. DWM, RWS and Norma did make it but I'm not sure if they still do so or not. Someone on this site that may be able to help you out obtaining some is gunbug.