Hi Ron
This sort of kit is so b****y hard to find that I'm grateful for anything that comes along. And expecting the tin to contain precisely what it contained originally is pushing my luck much further than reality will allow.
Over the many years that No 36 grens were in service, and in so many versions, it is not surprising that contents will be well mixed up. And some dets have been more than well used over the years,
So, some dets are aluminium, some are (apparently) copper, and a lot are aluminium with a copper coating that has worn almost completely away. Some have rubber bands on that have, amazingly, survived.
On a random small sample, two dets are clearly stamped DRILL and 111, one is apparently all copper , the other is aluminium but with traces of what seems to be copper but in reality is a varnish or shellac coating.
Hope that helps.
Alan1