LAGE Manufacturing, LLC. will soon be selling a .22 conversion kit that they have developed for the SWD Cobray M-10 and M-11 submachine guns.
This design uses your existing upper receiver and cocking knob with a drop-in barrel insert, bolt assembly, magazine adapter and modified UZI .22 LR magazines. The magazine inserts in the pistol grip mag’ housing just like the original 9mm magazine.
LAGE currently manufacture a range of slow-fire upper receivers for M-11, M-10/9 (a version for the M-11A1 is in development). These uppers slow the rate of fire from 1100 RPM to 600 RPM, making the gun much more controllable.
These guns are well known for eating through ammunition with their very fast rate of fire. The cost of these uppers are around $760.
Many thanks to Jeff for the information, photo and links.