As was pointed out earlier, shaped charges, in the form of HEAP ammunition are available in MT at TL 5:
TL 5 and 6 HEAP rounds use the ammunition table penetration listings. At TL 7 and higher, they start receiving penetration bonuses.
Shaped demolition charges in MT and Striker aren't available until TL 7. This is both historically wrong and inconsistent within the system.
Good catch!
As no definition is given in MegaTraveller for the various acronyms, I was not sure exactly what HEAP stood for. I was not sure if it meant High Explosive Armor Piercing in the sense of an armor-piercing round containing explosive, a round using a shaped charge, or what the US Army calls a High Explosive Plastic round and the British call a High Explosive Squash Head round.
However, that does lead to some pretty odd results. The tables in MegaTraveller have HEAP rounds for all artillery up to 30cm or about 12 inch, for mortars, howitzers, and high velocity guns. They also have KEAP, which I assume means Kinetic Energy Armor Piercing rounds for all of the weapons as well. It shows a 60mm mortar round with a KEAP penetration of 16 and a HEAP penetration of 18. The 60mm howitzer shows exactly the same penetration. Now, normally a mortar is going to have a lot lower muzzle velocity than even a howitzer, so why is the KEAP penetration identical? And what is a mortar doing firing KEAP ammunition to begin with, as least the small ones? The US Army did field a large number of 12 inch Seacoast Mortars firing Deck-Piercing rounds ranging in weight from 700 pounds to 1046 pounds, depending on the range desired. They were quite deadly weapons if used on a ship target.
The NDRC study that I mentioned in an earlier post did a fair amount of experimenting with shaped charges, and determined that a standard projectile fired from a rifled barrel had significantly less penetration with a shaped charge than an unrotated round. The rotational forces tended to break up the jet, with the result that a good shaped charge round fired from a rifled barrel would give effective penetration of its own diameter in steel plate, assuming a 90 degree angle of impact. Now, that theoretical 12 inch/30cm HEAP round has a penetration factor of 50, so that basically means that an armor factor of 50 equates to 12 inches or 30cm of steel plate. It does not matter if it is "hard" steel or "soft" steel plate either, as when it comes to shaped charge penetration, the controlling factors are mass and thickness, not plate hardness. That does lead to some odd results if you look at the weight modifier for an armor factor of 50 compared to an armor factor of 4. The armor weighs 80 times as much, but only improves protection by a factor or 12.5.
Now, at Tech Level 5 to 6, we are talking World War 2, so applying Real World data is, as far as I am concerned, totally valid. I have a lot of very hard World War 2 data to work from using Real World weapons to compare against what the MegaTraveller design sequence is showing. I also have the necessary conversion factors to calculate the armor protective differences between wrought iron armor, compound armor, steel armor, nickel steel alloy armor, Harveyized steel plate, Krupp face-hardened steel plate, the US Navy's World War 2 Class "B" rolled homogenous steel plate, and British World War 2 face-hardened steel plate. I also have some very hard data on the penetration of concrete by WW2 projectiles and fragmentation patterns of mortar and artillery rounds, along with protective factors for various types of field fortifications.
