The Dragoon wedge Ginormous showed is more like your Navy wedge. The proper position of the wedge is to be pushed in until the spring hook just snaps over the edge of the slot on the right face of the barrel lug. Ginormous's Dragoon looks to be past that point, but he said there were a lot of heavily loaded rounds fired through it, and it has probably hammered the wedge a bit narrower.
i also noticed that Pietta's wedge spring hook often doesn't have a very sharp hook, it is rather rounded, and it might benefit from a touch with a file. Do not attempt to change the slots in the arbor or the barrel, best advise is to only modify parts that are cheap and disposable. Wedges have always been considered disposable.
Thinning the wedge, usually the back face, with a file, carefully, you can get the wedge to seat further in until the spring hook reaches the right face of the slot when the cylinder gap is right, and the barrel is parallel to the cylinder and arbor. Check the front and rear face of the wedge for mark-off from the barrel and arbor slots, it might be a hint as to where to file and relieve the wedge. Keep the file cuts flat and smooth, and square to the width, don't change the taper. Thumb tight is fine, it need not be hammered, in or out, as long as the spring's hook retains the wedge from backing out by itself.
One reason the Pietta wedge fits so tightly, is that Pietta adjusts the length of the arbor to seat to the bottom of the hole in the barrel when the bottom of the barrel lug is aligned flush to the frame. If the wedge is tight when the arbor bottoms out, it's possible for it to be hammered so tight it's very difficult to remove.
Too bad Uberti doesn't fit the arbor as well, Uberti arbors are short, or the barrel's hole is too deep, and it's possible to drive the wedge in and close the cylinder gap, pinching the cylinder so it can't rotate. Theoretically, that can't happen to a Pietta, or an original Colt.
Go to VTIgunparts.com and order spare wedges, they are a necessary spare part, and can put the gun back in action if you lose one, or replace the existing wedge if it gets too loose eventually. You might also try an Uberti wedge.