Jaques d'Alltrades wrote:
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...

Wow! A one-pounder punt gun! Imagine the cloud of black-powder
smoke... Curious to think that those scary monsters once made
economic sense.

--
Mike.