Interesting 12g casing

[Spaceinvader]

Hello all,
I decided to finally get this cartridge ID'd after a few years. I found this at my feet while fishing a couple years ago 1-2 km downstream of a government/military firing range. At said range they do all kinds of stuff, artillery, armoured vehicles and small arms too. Its a big complex and they do experimental and "secret" stuff there too.

Anyways, it looks like a 12 gauge shotgun casing and is pretty much the same size. Its pictured here next to a typical 12g Winchester casing. The whole casing it blue and brown plastic. The odd thing is that there is no bottom, you can see right through it. I dont collect shotgun casings so this could be a normal thing, maybe the metal corroded off? Its seems to me kinda like some caseless rounds, but of course there is still much of the casing left! If anyone has info on this or something like it, I would be very interested to know what it is. Thanks, Rhys

 

[ANDY19422]

Looks like a standard 12g magnum load cartridge to me. On Google images it looks like some have a separate bottom disc.

 

[Spaceinvader]

Do you have some of the pictures Andy?