WWII German 20mm Aircraft Cannon Rounds for ID

[peregrinvs]

I don’t normally collect aircraft ammunition, but these were a bargain in a local antiques place. I believe they are WWII German 20mm rounds, but what else can you tell me about them? Thanks.

 

[Grzesio]

They are for the MG 151/20.
The fuse on the blunt nosed one is marked ZZ 1505 if I see correctly, so it's the 2 cm M-Gesch. m. Zerl., 2 cm high capacity demolition shell with a selfdestructor. Its original colour should be yellow.
The one in the middle is an AP, judging from the remains of the black paint and lack of other colour markings - 2 cm Pzgr. o. Zerl. (2 cm AP without a selfdestructor), filled with inert pressstoff (presence of a HE or incendiary charge would be indicated with a yellow or blue ring respectively at the bourrelet).
The third one, painted gray and with pointed nose piece, is a 2 cm M-Gesch. Ueb. o. Zerl. practice with inert filling, without a tracer or a selfdestructor.