The message
from Derek Turner somewhat@odds contains these words:

garden guns are not 20-bore nor any where near! they take a number 3
cartridge (.177 is No1, .22 No2, 9mm is No3) most garden guns fell foul
of regulations which set a minimum barrel and over-all length for legal
smooth-bore weapons. There are still a few of the longer ones about,
though ammo (being brass-cased) is very expensive. Need a part-two FAC
to buy/own one.

In my collection I've a No.1 bore shot cartridge...

--
Rusty
Open the creaking gate to make a horrid.squeak, then lower the foobar.
http://www.users.zetnet.co.uk/hi-fi/