Most here already know my primary collection interest revolve around INERT, large bore discarding sabot ammunition and torpedo related artifacts. Over the years I have been fortunate to have had a chance to build up my collection of specimens and reference material and most importantly meet and become friends with so many in this forum and the IAA.
I love learning and researching this stuff down to the last detail which is the reason for this thread. I have noticed that their seems to be at least 3 different variants of the 120MM M865 TPCSDS ( Target Practice Cone Stabilized Discarding Sabot) round.
So far, I have noticed a, “Long Sabot”, and two types of, “Short Sabot”, variants. One with a, “Pierced Cone”, and two with a, “Solid Slotted Cone”, assembly. I am pretty sure the, “Long Sabot”, with the “Pierced Cone Assembly”, is the earliest production round and the two “Short Sabots”, were developed latter and are still in use?
This picture shows all 3 variants side by side. I propped up the projectile on the far right. ( Sitting on a piston from the T72 Tank). I believe that they are positioned in the correct developmental order, the earliest on the left and the most recent on the far right. Note the differences in the sabot length, driving band(s), tail-cone designs, and point of attachment to the CCC (Combustible Consumable Case).
This pic shows the,“Long Sabot w/ Pierced Cone”, on the right and the late model, “Short Sabot w/Solid Slotted Cone”, on the left. Note the difference in attachment points to the cartridge case. The, “Long Sabot”, is designed top fit OVER the case, and the “Short Sabot”, is designed to fit IN the case.
This picture shows both the early variant, “Long Sabot”, & mid production, “Short Sabot”, both designed to fit OVER the CCC.
This photo shows the early variant “Short Sabot”, next to the late variant “Short Sabot”. Here you can clearly see the attachment design differences. The late variant, “Short Sabot”, has a nylon band that snaps into place inside the CCC.
This photo is of a different 120MM tank round but clearly shows the way its driving band is designed to snap into place with the CCC.
The 2 different tail cone assemblies, “Pierced Cone”, and “Solid Cone”. Both designs were made for TP ranges. These tail-cones were scientifically designed to be a range reduction component, limiting the travel distance of the round to under 10 miles. Both the, “Pierced” & “Solid”, stabilization tail-cones were designed to use the aerodynamic LKL ( Loch Kegal Leitwerk) principle. For the LKL principle to function, the holes/slots in the tail-cone are machined to a size where at super high velocities, they are “Aerodynamically Open”, and air can pass threw them with out a problem. As the sub-projectile speed slows over distance, the holes/slots “Aerodynamically Close”, at a certain velocity. This leads to a increase in drag, and the sub-projectile becomes unstable, where it starts to tumble and fall to the ground after 7000 to 9000 meters. The LKL principle typically starts after 2000 meters. Up to that point, it has the same ballistic trajectory as it tactical counterpart. (Above LKL info learned from Jane’s Ammunition Handbook)
Tail cone removed & inverted to highlight design differences.
It is amazing the amount of research and design that goes into the creation of these rounds. ATK and GD-OTS are my 2 favorite ordnance companies and do so much to provide the best ammunition in the world of all calibers and designs to our troops (HEROS) overseas.