Thx for the offer Dave. I'll PM my postal address for those FN designs.

Case capacity was only around 65% with 2209 (guestimate) hence the wads which then filled the case.

I bought the wads for the .416 Rigby as I just 'got the feeling' that the reduced loads gave erratic ignition. I will write up the .416 Rigby results when I get time to do more range testing.