Large Trounds


#1

I have 3 large Trounds that I would like more information on.

#1–Length 101.32 mm (3.989 inches)
Three 7.13 mm (0.280) Ceramic bullets 31.77 mm
(1.25 inches long.
The bullets as can be seen in the scan set at an
angle.
This cartridge was designed to be fired down an oil
pipe to break up the hard rock so it could be drilled
more easily. The ceramic bullets are set at an angle
so they align with the “Mud Holes” in the rotary bit.

       Who made these? Are they still used?

#2–Length 70 mm (2.75 mm)
This and the next one are, I think, part of the TRW
HIVAP , 30,000 RPM system. It has an 8.96 mm
0.353 lead bullet

      Need more information.

#3–Same as above, excpt this is a Tri-plex load. It has 3
4.19 mm (0.165 inches) holes. They are flechettes
but are Hollow Points.
.
Need more informaton

Both #2 & #3 use a .22 blank as the primer. Headstamp is a U with a dot in the center.