So it was basically a glorified BB gun?
Don't look down your nose at it; it can push a .46 caliber round into the area of 535 fps and be able to put a hole in an inch of pine from between 100 and 150 yards. That glorified BB gun will kill you from over a football field away and would actually be banned in quite a number of countries.
To put that in perspective, a .45 caliber 1911 can fire a round at 830 fps and has a maximum effective range of just 55 yards.
Have you seen some of the modern modern equivalents?
.357 .45 .50 The Girandoni holds up amazingly well in comparison despite its age.
Now, to take issue with the poster, there were about 1500 Girandoni rifles in the world. In America they were so rare that researchers were actually able to find and identify the one that Lewis and Clarke used with a very high degree of certainty. At the time there was one air gunsmith/shop, Isaiah Lukens, who apparently managed to get hold of one (perhaps for a little 'design inspiration'
), and the number of guns like this that he produced was vanishingly small because there just wasn't any demand for them.
I guess nobody needed a high capacity magazine.