That's either the one, or a relative of the one that Eisenhower had rolled around Korea in 1953, to convince the North Koreans to get serious about armistice talks. I saw it go up and down the road several times.
Sounds like you were there. If so, I'll defer to your experience. I wasn't even thought of at that time;).
From my perspective, Korea was a mess that Truman could have prevented. If anyone had atomic credibility at that time, he did, and didn't make the best of it. If I were him, I would have delivered a very clear message to China in these words: "In 1945 I had two atomic bombs and I gave the order to incinerate two Japanese cities...I have more than two atomic bombs today. If you know what's good for you, stay out of this!"
Moving the 509th into the area was a good move, but IMO, it didn't get the point across adequately.
The shell was an anti personnel shrapnel round.
I could see it exit the bbl and go down range.
The shell looked like to be the size of a 55 gallon drum.
The targeted area was probably 4 miles away. But if you put enough bags of powder in it you can get out 18 miles. - Tom