The pistol, POSSIBLE SPOILER!

Well, eventually they'd run out of ammunition, I guess, unless airlines in the 60's supplied their crew with plenty of ammunition, which doesn't seem likely. Probably it was symbolic because Jonesey's possession of the gun was used to nearly kill Barnaby after falsely accusing him of attempted rape and murder. Maybe it was cryptic support for the idea that, unless everyone could have a gun, one gun would give inordinate power to the person who possessed it. I also think the captain realized he'd made a mistake when he tried to exercise authority by using the gun. His authority came from international maritime law. It's the law that gives the gun its authority--not the other way around.

The gun represented all the power struggles that went on that the captain wisely felt they needed to avoid. Instead of one faction trying to hold onto power with the gun they'd all have to make decisions together.

Typical late '60s, early '70s type of "all together now" rainbow power mentality...