
Okay, as Flintlock, Blake, and others noted, the whatziss was the guts of the rotary magazine from a Mannlicher-Schoenauer rifle, specifically the M1903/14 Greek rifle from the 1927 Breda contract. Here's some more pictures to satisfy your need for gunmetal and brass...
This is what the magazine looks like loaded, from behind. It holds 5 rounds. The rounds in it are .308 Winchester because they'd fit well enough for the picture (but are too wide when the magazine is installed in the rifle) as I don't have any ammo for the rifle at this point.

Complete with teh "Hair of Approval" from a Castle Argghhh! Internal Security Specialist (in this case, Lizzie).
This link is to a side view of the magazine.
This link is to a shot of the action with the bolt closed. The "Breda 1927" mark is barely visible on the receiver side rail.
This link is to a shot of the action from the other side, with the bolt open.
And, lastly, a link to a close-up of the receiver, showing the Greek markings.
Rather than go into the Austrian/Italy/Greece aspect of things, discussing the various design derivations from other rifles, etc - for the nonce I'll send you to [Oops, my goof, Ian] Tamara K's write-up and Oleg Volk's write-up pictures of the rifle, if only because his pictures are better than mine, and I don't have the time to expand the post further. Besides, it's good to link to others and play friendly!



Thanks for teaching me something today.
P.s. Once I got my new system running, one of the first things I did was download Tam's yachting photograph to my hard drive. Yah, she's a good-looking wummun there , but what's better is the grumpy expression on her face in that pic which will forever endear her to me.