Been taking a look at the latin phrase, Invent et Fecit, found on this Girardoni found in a German museum.
The meaning is unambiguous; Invent et Fecit means this item was itself manufactured by the inventor.
Doing a search, what predominates are watches, with a Swiss maker, Journe, leading the pack. In this modern usage, it means that all of the parts used in construction of the watch were also made by the same company as designed/invented the watch.
There has also been usage of this phrase in gun making. In particular Josph Manton (perhaps the most famous London gun maker circa 1800). His guns are also marked Invent et Fecit. See this example http://www.flintlockcollection.net/joseph-manton/
One thing about the original Girandoni made for the Austrian army that everyone should be able to agree upon: the Model 1780 military repeaters were hand-built by the inventor himself - this point is made absolutely clear in Haller.
Over the years, I've maintained that Eldon Wolff was undeniably correct when he wrote that no undisputed examples of the original Girandoni have been found. As we all know, some modern researchers came to the conclusion that the often seen 11mm Girandoni as described by Baker/Currie were original Girandoni made and that this was what Meriwether Lewis carried. Where they were right is that, yes, the air rifle carried by M. Lewis was more likely than not the same as described by Baker/Currie. The only mistake was in pronouncing that these were also original Austrian Military weapons hand-built by the inventor, Girandoni. They weren't. They were made in England or at least the parts were. Looking over these 11mm Girandoni arms, it seems perfectly clear that they are products of modern technology of the industrial revolution, i.e. they are not hand-built.
With the discovery of this "Girardoni Invent et Fecit" 1.4cm air rifle, that we now have a prime candidate for an undisputed original Girardoni made Girandoni.
I'm by no means ready to make any sort of declaration on this airgun. We've waited long enough for a proper candidate so there's no need to rush. The first thing is to confirm the large caliber, but, even that doesn't go all the way. We know that some 1500 original Invent et Fecit Girardoni military model 1780 were made. We've found one, there has to be more. And now with the id tag of "Invent et Fecit" it should be possible to conduct a pretty good search. Before we would have to look and ask about any and every Girandoni type, now there's a simple and direct question.
If more Invent et Fecit Girardoni can be found, then Wolff's contention of no undisputed examples of the Girandoni military model 1780 can finally be closed.