An interesting presentation, and some new and fascinating theories. However, the Girandoni air rifle was not the one owned by Meriwether Lewis and used on the expedition. His rifle was made by Isaiah Lukens, clockmaker in Philadelphia, who made the clock in Philadelphia's liberty Hall. Several other air rifles by him are also known. The Lewis & Clark rifle had a replacement mainspring and a repair to the ruptured air flask, both made by Private john Shields of the expedition. Untrained, 2000 miles from civilization, with little more than a bellows and a charcoal fire, he forged, tempered and welded the product of the Philadelphia clockmaker. Lewis said the rifle had the same caliber as the expedition's other rifles. Despite popular opinion, these were not the Model 1803 rifle, but the earlier Contract Model of 1792, and were in 45 caliber. It probably had a set trigger. Somehow the air rifle got back to Lukens and was part of his estate when he died in 1847. Item #95 of the inventory of his effects is "1 large air gun made for and used by Messrs Lewis and Clark in their exploring expediitons". It vanishes from history after that. There is no dearth of claimants for the title of Lewis and Clark rifle; Dr Robert D. Beeman extensively researched the question and his article apears in Airgun Revue #6. There are several other articles by other researchers, mostly in "We Proceeded On, the official publication of the Lewis and Clark Trail Heritage Foundation". Dr Beeman reaches the conclusion that the Lewis and Clark airgun is one now in the VMI Museum. His reasoning is persuasive, but my opinion is that there is insufficient provenance to any of the claimiants to give them title to the Lewis and Clark gun.
Incidentally, the only firearm positively identified as coming from the Lewis and Clark expedition is a trade musket given to the indian chief Twisted Hair and buried with his son. It was recovered in 'ruinous' condition in 1960 and is now in the Clearwater Historical Society.