The "Tinian Shot" - are there any additional sources?

Back in October 1993, in his monthly 'Commentaries' newsletter, Jeff Cooper described what he called the 'Tinian Shot'.

Anyone who knows anything about marksmanship knows that it is something one does not boast about. You may remember that Billy Dickson always attributed his long shot on the Indian to pure luck, and this was always called mere modesty on his part. Other examples will occur to you. However, if you would like a conspicuous case study of how it was done, consider the famous "Tinian shot" delivered during the occupation of Saipan and Tinian during the Pacific War.

When we had taken Saipan, it was planned to move across the intervening straight and land on the north end of Tinian Island, utilizing as much supporting artillery as we could muster, in addition to aerial bombardment and naval gunfire. To bring this off we moved all of the guns available on Saipan to the southern tip of the island and set them into position to fire across the straight on targets selected as appropriate. The smallest guns were placed as far forward as possible. In the case of the 75 millimeter pack-howitzers, this was right on the beach. Now the 75 millimeter pack-howitzer in not much of a cannon. Its principal virtue is that it is light and compact and can be moved around in difficult terrain with minimum effort. It fires a 3-inch shell at high angle to a fairly modest range - say, 2,500 yards. When all was ready, the signal was given to commence registering across the straight, starting with the little guns first. One battery of 75 pack-howitzers fired one round, which arched over the separating water and came down almost vertically.

It so happened that I was present at this time, riding offshore some 3,000 yards to the east of the straight. I was looking right at the point of impact. The result was unbelievable. The first thing I saw was a white, hemispherical flash, perhaps 500 yards in diameter. Out of this boiled a huge black column of smoke thrusting skyward into the traditional mushroom cloud. There was no sound, but we could see the shock wave moving out towards us across the water in a curved pattern. In a moment that shock wave struck the escorting destroyers and heeled them radically over in the water. The curve raced on towards us and we turned away and covered our ears. What hit us then is indescribable in words, but it was a sensation one is unlikely to forget.

What evidently happened was that first ranging shot from the 75-millimeter battery had found its way down some sort of ventilating shaft into the main ammunition depot on the north end of the island, and everything went up together.

I never heard what reports were circulated around amongst the artillerymen on Saipan, but one can guess at a number of appropriate wisecracks:

• You want me to do that again?

• Now you guys with the big guns can have your turn.

• That was Number One gun. Now I am going to try with Number Two.

• Why didn't I think of that last week?

• Everybody break for chow.

And so on. That was the "Tinian shot." Anytime you feel like bragging about something, keep that one in mind.

It's a great story, and one I relished.

I'm doing some research for a forthcoming novel, and something like the 'Tinian Shot' will come into play.  I'd like to find out more about it.  Does anyone know of other sources that mention this incident, and perhaps shed more light upon it?  Can anyone identify the unit(s) involved?  If so, please let us know in Comments.

Thanks muchly.

Peter