Ok, I am pretty sure no one should object to this as I am certain it is 100% AMMO RELATED :-) This is a interesting 105 MM APFSDS projectile designated the XM797. It was designed to be a target practice round to mimic the flight characteristics of it tactical counterpart of the era, the M735. The interesting thing about this round is the design concept of the sub projectile flechette. Like the 120 MM TPAPFSDS rounds, the military needed a 105 MM TP round that exactly mimics the tactical round while at the same time reducing its over all travel distance. Since most tank practice ranges are shorter then the greatest distance tactical rounds travel, they designed this round to become balisticaly unstable at a shorter distance. Many 120 MM TP APFSDS utilize a solid or ported coned tail section to reduce overall distance vs the tactical finned tail section. What is fascinating by the design of the XM797 is the subprojectiles nose cone or windshield design as well as a pre fragmented body. What they did was design a windshield that heats up from balistic forces, melts and then fails. When the windshield fails, it also splits the projectile in half longways which obviously causes the projectile to become unstable and fall apart, landing short after a known distance of perfect trajectory. I hope that made sence?
Anyhow, here is a quote from a web site on its design. It may make more sence: "The XM797 is a proposed training round for the 105mm M735 high velocity projectile. This projectile is designed to have a trajectory that closely follows that of the M735 yet have a maximum range of 8km. To achieve this performance the XM797 is designed with a nose cap made of zinc alloy which, due to structural weakening caused by aerodynamic heating and centrifugal loads due to spin, is supposed to fail and result in the projectile breaking apart. "
This photo show the nosecone removed. If you look carefully, you will notice a thin line running down the lenght of the subprojectile. This is the prefragmented line that causes it to split in 2.
This photo shows the XM797 (bottom) next to its tacticle counterpart the M735 (top)
Here is a group shot of 105 MM & 120 MM tank fired APFSDS rounds. Note that most 120’s utilize a CCC (Combustible Consumable Case).