Vlim's Magazines
 

Sorry to start a new thread. I just could not find the photo Vlim posted of the hi-cap mags he was inquiring about.
I looked around, These are Madsen M50 magazines. A locking block has been added to them in order to allow them to function in another type of subgun. I am uncertain of which subgun though. It must have a large magazine well though, like an MP28 or MP34.