Hi Naun
Thanks for the additional photos. My pistol's bore is also drilled through back to just behind the vent hole. Most are. But it's still a decorator only. Most of the locks on these guns will function. But the mainsprings are usually too weak and the frizzen too soft to produce much of a spark. For decoration purposes it was not necessary to go to the additional expense.
Your guns:
1 A European tourist item, as discussed above.
2 Looks like an attempt to copy an original French ANXIII pistol from the early 19th Century (?) Could be an original Belgium made copy from the period (?)
But difficult to tell from the one photo. Would need closer pics. Especially of the lock with the frizzen in the open position showing the pan and vent hole. How many lock bolts are on the left side of the stock ? One or Two ? In any case, the ramrod is wrong. Too thin, and incorrect style decorative tip. But could be just a later replacement.
3 This Afghan styled/decorated gun is likely also a decorator piece. These have been, and still are today being sold in various bazaars in Afghanistan. See photo below. While the locks will somewhat crudely function, the barrels are usually just a piece of decorated pipe. It seems that many were brought back to the U.S. by returning Troops from the Afghan campaign. And eventually resold. The short barrels made it easier to transport back home. Virtually every 19th Century original shooting guns had much longer barrels, unless damaged and shortened during the period. Many of the tourist items made during the earlier part of the 20th Century actually were made with a combination of original surplus and new (for then) parts. Until sometime in the 1970's when the surplus started to dry up. It often takes experience and knowledge to detect the originals form the tourist copies. Especially with these Eastern guns.
4 Hmmmm. Not sure on this one either without more detailed photos. From the one photo, it looks like it was assemble maybe sometime during the 20th Century using surplus parts. Looks like a musket stock and lock that had a broken fore stock and missing it's barrel. With the brass blunderbuss barrel added at some point. Notice the barrel sits too high in the stock. And appears to lack a hole for a ramrod (?) In any case, it looks to have been assembled by an amateur gunsmit for decoration purposes.
Hope some of this helps.
Rick