I'm fairly certain I heard that our first astronauts were given these and perhaps some early fighter pilots. There was also a scene in MASH that alluded to this but it didn't have anything to do with reasons for the other two to have them.
I just found this out recently and got to me. The tradition is to place a bullet and match in a flag pole "truck" or top decoration, maybe a ball.
Tradition: The last defender is to retrieve the truck and remove contents. Using the match, burn the flag and the last bullet, kill themselves.
Now, I checked it and most offer a razor rather than a bullet -OR- all three. But, I would think the whole affair is gruesome, but anyone may rethink doing themselves with a razor IMHO. I found repetitive answers but not a definite one, like why the tradition got started in the 1st place. It appears more as a rumor, but if it is, then under military traditions it serves a practical or patriotic one. -----Willy ![]()
http://www.snopes.com/military/flagball.asp

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