Nagasaki atomic bomb safety plug


Attention, nuclear bomb collectors!!! This unique item is for your enjoyment, very rarely seen on Ebay or at gun shows.


This atomic bomb safety plug is something I coincidentally know a little about through my friend Clay Perkins, a retired physicist living in the San Diego, CA, area. Clay is a historian with a great interest in the Manhattan Project and the nuclear development that followed WWII. He also has a world-class firearms collection and is slowly warming up to cartridge collecting.

A few years back, he purchased one of the three (or maybe four) safety plugs that were installed in the “Little Boy” atomic bomb carried on the Enola Gay B29 on the 6 August 1945 Hiroshima mission. His plug came from Morris “Dick” Jeppsen who, as a second lieutenant, was the assistant weaponeer (not bombadier) on the mission. One of Jeppsen’s tasks was to enter the plane’s bomb bay after takeoff and remove the green-tip safety plugs, which prevented electric circuits required for bomb detonation from being completed. He replaced the bomb’s safety plugs with red-tipped arming ones, and put the safety plugs in his flight suit to be saved as mission souvenirs. After the mission, he kept one and later, as he was getting old, decided to auction it so he and his family could enjoy the proceeds while they still had the time. Perkins acquired the plug and formed a lasting friendship with Jeppsen, and introduced me to him. I have a large photo, autographed to me, of him standing by the nose of the Enola Gay in 1945.

I got involved in this atomic bomb history because Robert Mainhardt, the “M” in MBA (Gyrojets, etc.), was a weaponeer himself during and after WWII as a result of his experience as a member of the scientific staff of the Manhattan Project at Los Alamos. As a civilian, Mainhardt could not participate in combat overseas, but he did fly many training missions during testing in the U.S., and he participated in several postwar nuclear tests.

The green tipped safety plugs are great ammunition collectibles, and I like the fact that at least one is in a private collection. BTW, in case some might not remember, the General Groves mentioned on one of the descriptive cards shown was the officer who directed the entire Manhattan Project. It’s not surprising that he got one of the plugs.


The General who donated the atomic bomb plug was, Lt. General Richard Hulbert Groves, USMA Class of 1945. He was the son of Lt. General Leslie Richard Groves, USMA Class of November 1918. It was General Leslie R. Groves who had charge of the Manhattan Project. Earlier he had been in charge of the construction of the Pentagon.


GWB; Thanks for the correction. I should have noticed that.



There is one safety plug from the Hiroshima bomb out in private hands, at least it used to be. It was the prized possession of Leon Smith one of the 3 Tinian weaponeers. He lost the coin flip to Morris Jeppson for the Hiroshima mission. Morris gave him the plug upon return. Leon was a fixture at the Defense Nuclear Weapons School at Kirtland AFB. He used to pass the plug around during his lecture on the early years of the program for students like myself to marvel at.

He set the frequency for the radar altimeter on the weapon and for a short period of time was the only person alive with that knowledge.

He was pleasure to listen to and was quite active even in his advanced years. Unfortunately he passed away on 14 Oct 2012 at the age of 92.


Incredible history!