Ordered a copy of Erich Gabriels book Die Hand-un Faustfeuerwaffen der habsburgischen Heere from Vienna which came in yesterday.
This is the authoritative book on the holdings of the Vienna military museum. It includes one of the model G repeaters identified as an original Austrian military repeater air gun. I have long had a copy of the section on the Girandoni, sent by somebody to prove that these G guns are the real deal. Of course, when it comes to air gun history, the opinion of august authorities is just another opinion to me, but, I still wanted the entire book in order to get a better view of what an Austrian military gun from the 1800 era really looks like. In particular, I wanted to see if there were any clearly Austrian military features of these G guns. The short answer is: no.
There are some very distinct features of the Austrian military firearms. There is a very distinctive elongated-S left side plate on almost every gun of this era. There is absolutely no comparison to any of the Austrian muskets. There is less difference compared to the jager (hunter) rifles, but, still, there is not a single feature found on any Austrian musket or rifle from the 1700 - 1850 era that matches any feature of the G guns.
Rifling: all the jager rifles are 7 grooves. There are some 12 groove rifles but these are 1850 or later.
Markings: The Jager rifles usually have some markings but nothing that appears to be a serial number. When there are numbers, they are either one or three digits long. There are no numbers greater than 3 digits on any other Austrian military firearm of this era. I have also yet to see any mention of a double eagle proof mark. There are mentions of some unidentified marks. For the muskets the markings is always keine (none).
Also distinctive of the Austrian military weapons is the absolute plainness of features. The G gun, as seen in Baker/Currie, has some decorative features not seen on any Austrian weapon. The muzzle cap on the G has some fancy curves that require careful inletting of the stock. The muzzle caps of the Austrian weapons are all smooth in the same area. Which makes sense. The Austrian guns are purpose made and have zero decorative features that would increase the time (money) to make them.
So, of course, none of this proves my point that the G guns are not of Austrian origin, but, it is very clear that there is not a single distinctly Austrian military firearm feature to be seen on the G guns either.