I have found Roberts very helpful - I have an old WJ Jeffery double 410 and they gave me the full history.

And picking up on your comments re reloaded slightly hard to close / leaver not snapping to the middle On the other discussion i had the same on 7x65r. New RWS cartridges, easily closed and lever shaped across, on reloading some were a bit sticky. I found that the case length had increased, not by much, and not out of spec but just enough interfere with the end of the chamber. At the next reload I made very sure that the case holder had firm contact with the bottom of the die, and then trimmed them to length. Next batch no issues at all, and indeed were shooting even better.