Hülsendeckel, or consumable cone adaptor, must be and is a part of production rounds. You cannot assembly a round without it. It is a part that is being glued to cylidrical part of case after filling propellant. Yes, there are some novel ideas of partition of 120 mm cartridge, but DM 33 is not an example of that.
There are few patents that could be connected with 120 mm DM 33 project because of timeline and general similarity. That coloured diagram is from one of those - and it is just on, AFAIR, steel case around projo's tip. But there are few more, on making predetermined breaking points (present on DM 33 - check here), on changing tip properties via heat treatment, on fin section design etc. IMHO there is stron possibility that diagram posted by BkktMkkt's shows a projectile close or identical to DM 33.
As for your last notice, this could be an answer:
A surprising increase in the effectiveness when firing on multiply armored targets, especially on spring mounted armor plate, has been achieved by means of the proposed increase in the diameter in only one tip area, which has been proven through testing. Conservative estimates lead to the conclusion of an increase in effectiveness of more than 10% in connection with this improved kinetic energy projectile, compared with customary kinetic energy projectiles.