EOD; Yes, I have interviewed David Dardick’s son Steve, who was the Tround International, Inc. plant manager and a lot more. Steve has two sons and the three of them are keeping the open chamber concept alive, although inactive for the time being. The family is very supportive of my book project and are helping a lot. Through them, I’ve been able to get much firsthand information, documents, photos, etc.
On the Cal. 50 Trounds for a U.S. Navy R&D contract, I don’t have any hard info (yet, but I will) about the white plastic caps, but I’m sure the rounds were not fired with those in place. The front cap bulges out a bit, slightly increasing the OAL, which would not work. And the plastic would jam up the gun’s action. One of my .50s has the white caps on both the front and rear over the primer. I have 22 variations of these and none has an electric primer, so the rear caps must not be to protect against stray electricity. Dardick did have a contract with the Brits, so it’s not surprising that a few of the .50s should show up there.
Dardick’s hard-rock-drilling system, a.k.a. “Terra-Drill,” with its triplex cartridges is very interesting. I grew up in East Texas in the middle of oil refineries and oil wells and picked up a little knowledge about them without really trying. Drilling oil wells costs a ton of money, and time is money. When drill bits wear out, the entire stack has to be pulled out so the bottom piece with the drill bit can be changed. This takes a lot of time and the drill bits are very expensive.
Dardick’s idea was to increase the life of the drill bit by 10 times and increase the speed of the drilling in hard rock, e.g., Taconite, significantly. He designed a system with a 5,000-round magazine of triplex Trounds. When the drill bit encountered hard rock, the system began firing the Trounds, each with three ceramic projectiles in clear sabots. The projectiles were ceramic so the drill could pick up their shattered remains along with the other rock it was drilling through. Metal projectiles would have jammed up the drill.The projectiles were loaded at a slight angle away from center in the Tround cartridges for the correct dispersion and the gun barrels were set at the same angle. They came out of the barrels at 4,500 fps, impacted the hard rock at slightly different times, shattered, and set up shock waves that fractured the hard rock up to a depth of 20 inches or so, depending. This allowed the drill bit to drill through pre-fractured hard rock and a higher rate and with less wear. Details will be in the book.
Here’s a pic of a clear Lexan cartridge dummy. Note the divergent angle of the three ceramic projectiles. I just weighed one at 46 grains, but there are variations. The one I just measured has a diameter of 0.2420 inch and an OAL of 1.2350 inches.
Here are three other pics of the Dardick Tround system. The first is the Dardick drill bit group with one of the three barrels easy to see.
The second pic shows the assembly in an Ingersoll Rand T-4 rig:
And the final one shows the Dardick Tround “Terra-Drill” being unloaded from a flat-bed 18 wheeler.
I’m really just at the beginning of this and will have a lot more detailed information in the book.