Rigbymauser/AKMike

As you appear to have Hoyem and Fleming I can only support your observations that it would appear to be a necked down .577

The shorter case would probably be Westley Richards but the longer case may, as you say have a Scottish connection

The .500 Ex on the barrel flats is clearly of little use

Good luck with your Africa trip, you certainly have a top class calibre/ rifle combination for your trip

Good luck

Tony