Dale,
Both calibers should fit in the drum... if 9mm doesn't fit, then it may not be a genuine drum, but rather a reproduction drum that will only hold a few rounds... the drum part won't function at all on the repros.
Authenitic drums vary in price depending on condition and who wants them. I have seen them sell for as little as $550.00 to as much as $1200.00 over the last two years. To properly use the "Trommelmagazine" TM-08 it requires a loading tool that will also run several hundred dollars.
The other two objects in this photo are a dust cover, and an adapter for an early MP-18/28 Schmeisser submachine gun that also used this magazine.
Check Gunbroker.com and AuctionArms.com because I think there are a drum and a loading tool being offered at this time on one or the other.