I have quite a lot of different .20 projectiles including lead balls and these Sheridan slugs. Can't remember where I got them but they have a sticker on "Jefferys" £3.99. See pic...
Baz
BE AN INDEPENDENT THINKER, DON'T FOLLOW THE CROWD
Sincere thanks for all your replies and valuable information. It was just idle curiosity really as I was thinking of the .177 "cat slugs" which I used to use back in the 1950's due to their cheap price. They were also very inaccurate in my Webley Junior pistol and I soon learned to buy the more expensive "waisted" type.