My apologies on the "trigger spring" - I didn't catch the photos of the second pistol. I was talking about the first pistol pictured.
On the second pistol - I had one very similar to this. It was a screw barrel and it had no proof marks. The only markings that were on mine were "cast steel" - I always figured that it was probably Belgium. On the one I had, the barrel was round up to where it screwed on to the breech casting and it transitioned into octogon at that point. It would have required a wrench that slide over the end of the barrel and utilized the octogon portion to unscrew it for loading. Not all, but a good majority of the screw barrel pistols often had a bullet mold furnished with the wrench on the end of one of the handles. I have a small bullet mold that was passed down through my family that has a square lug on the end of the handle at a right angle - this was to slip into the end of the barrel that would have had "octogon rifling" to unscrew the barrel for loading. Many of the screw barrels had a cupped breech which took only so many grains of powder and the ball was set on top of the charge. The barrel was then screwed on - the ball being just enough oversize of the rifling that when the barrel was tightened down, the ball "stayed put" when the rifling in the end of the breech of the barrel tightened down on it. Patches wee not commonly used - these were strictly for "up close" use.
If a pair of '51 Navies were good enough for Billy Hickok, then a single Navy on my right hip is good enough for me . . . besides . . . I'm probably only half as good as he was anyways. Hiram's Rangers Badge #63