I thought I'd also PM this to the BASC contributor but post it here as well.
So it is hoped that those with such guns will follow this up as an "economic consequence". I have looked yesterday on the Eley website an find that there are no steel cartridges for 12 bore guns in 2 1/2" that are the shot size allowed on clay grounds which is mostly maximum English #6 or of the maximum payload which is 28 gram. Yes there's 30 gram English #4 steel but no clay ground will allow such that I know of. Ditto for 12 bore and .410" gauge.
Hull Cartridge sell their Comp-X steel in 65mm but this has 21 gram of steel English #7 and clay grounds I have spoken to that have tested it describe it as "useless". And again there are no Hull steel clay 16 bore cartridges in 70mm with suitable smaller shot size for clay ground use. Nor do there appear to be any at 2 1/2" chamber 16 bore steel cartridges in any shot size.
So irrespective of clay shooting being outwith BASC's remit there does need, please, to be a study of just what 2 1/2" steel clay loads are available and what 2 1/2" steel 16 bore cartridges of any type be that clay or live quarry. And of course other SD members reading this may also need to check if suitable steel in both shot size and payload weight exists for their 2 1/2" chambered guns be they 12, 16, 20, 28 or .410". As they may not!