Here is another Jingal photo - even allowing for the small average size of the Japanese man in 1900, the guns appear huge as you say:
Not so sure about the Boxers using any type of cannon. You are right in saying firearms were invented in China but the boxers were mainly peasants with no military experience.
I mean I for one could not fire a black power muzzle loader! At least not safely. Regards, Pa
I once saw a Jingal replica and the man who made it was around 5ft 7ins tall. It was....1979 (!!) and I thought it was a joke at first. "They couldn't fire them standing or kneeling without support" he told us "They are called 'wall guns' because they were rested on walls" The gun would have been around the 7ft length mark. Compared to the Japanse and average height of time then, yes, those jingals must be 7 feet at least.
Incredible the powder weapons they came up with. Some are mentioned on this Wiki entry. Lots of scope for gamers!