I think I posted something on this subject some years ago, but I recently took some photos so I thought i’d post them. I enjoyed the Ramjet projectile discussion so I though you may enjoy this.
When I worked at the USAF Armament Division at Eglin AFB FL back in the late 1970s, an engineer I didn’t know walked into my office.He had heard I was interested in odd ammunition. He was retiring and had something he hated to throw away. He handed me a box and in it was the round below and a large spool if 16mm film. The label on the film is pictured below. He told me that it was part of the development of a multibarrel gun for the A-X program which became the A-9/A-10 competition and resulted in the A-10 Warthog.The engineer said the concept was pursued because it allowed the gun to be much lighter than the GAU-8 and potentially a very high velocity projectile with greater armor kill capacity.
The rocket has folding fins and slides into the case (which is steel) until just the blue part of the nose is exposed. I eventually had the film put on a DVD, but it is firing trials and all it shows is spots of flame and smoke going downrange and mostly missing a huge target. no real image of the weapon.
Some years later I called the Armor Research Institute (now the Illinois Institute of Technology Research Institute (IITRI)) on behalf of a friend, and I enjoyed the head of their museum who had worked there for many years and was now retired. When he found out I was in the USAF he said he may have something I’d like. A few days later he called again. He had gone out to their junk yard and dug out the end of the barrels of a five barrel cannon. He said that it had been a display in their lobby for many years, and had eventually been cut up. He said it had been a test of a gun boosted rocket for the USAF. I soon received a box with the barrels shown below and the tag pictured.
In spite of some research, the only additional information I could find is the article below which was sent to me by Fede (of course!!!).
Like the ramjet boosted projectile, I am sure it isn’t a new idea and somebody out there has other examples.
I have no idea how the 38mm gun is tied up with the 40mm projectile.