Jeff, drop me an email. I just finished a contract with LockHeed and met this really neat old guy that could talk for years about button bombs and gravel mines. Which according to hom were not the same thing. The button bombs were sensors and/or sensor signal. There was one gravel mine (are we all seem to call it that) was made at Rocky Moutian Arsenal and it was also a sensor signal. got some data on it. The button bomb project did not last every long even though thousands and thousands were made, an electronic cmpany made them, am suppose tog et some more details on that too.
As for gravel mine, 75% of them were made at Cornhusker and the rest at Iowa AAP.