It seems that leather canons were widely used by the Swedish Army during the war 1618 – 1648.
A Biography of Gustav Adolf mentions the following (rough translation by me)
“Instead of the common heavy cannons, where 16, 20 or even 30 horses were necessary for transport, he (Gustav Adolf) used light artillery, the so called leather cannon, which among other advantages had a high firing speed. Whereas Tilly never managed to make use of more than 30 canons, Gustav Adolf made at Breitenfeld* use of about 100, later even of more. These light cannons were assigned to cavalry as well as to infantry and increased the combat strength of these formations considerably.”
*Breitenfeld, a small village in Germany, near Leipzig. 1631 there was a battle between Tilly (40.000 soldiers) against Gustav Adolf (47.000 soldiers). It was the first battle, where Tilly was defeated and he lost 26 cannons, 12.000 men and his whole baggage. The German Protestantism was saved.
The German Historic Museum in Berlin
www.dhm.de owns 2 cannons from Sweden, described as follows (sorry, could not get hold of a photo)
1)
1 ½ pounder Leather Cannon
dating: between 1620 and 1650
country of origin: Sweden
dimensions: total lengths: 202 cm, bore 6
material/technic: Copper, iron, hemp, leather
2)
1 pounder Leather Cannon
dating: between 1620 and 1650
dimensions: total lengths: 196 cm, bore 5,4
material/technic: Copper, iron, hemp, leather
This might give at least an impression about the dimensions…