Unknown 20mm cartridge

I found this photo on the internet. The original poster (on a forum that I’m not registered on) was looking for an ID.

it looks similar to a 20mm Hispano. However, it appears to be semi-rimmed. The case profile also looks wrong.

Can anyone ID it?

Thanks for any info.

Falcon, it looks like a 20x110 H-S to me, likely a US M21A1 case. Also, if you look at the picture the semi-rimmed effect is apparent, but the shadow doesn’t lie.

Thanks Fede, I think you’re right there.