Leica Super Angulon 21mm f4 question

[Anton Lukoszevieze]

Can an M mount Leica 21mm f4 lens be used on a screw mount Leica if the mount is removed? I have read about this possibility, but cannot find a definitive explanation online. thanks

 

[John Koehrer]

The original 21's were ltm's with a screw on adapter secured with set screws.
From "Identifying Leica Lenses" by Ghester Sartorius.
"Leitz never really produced a bayonet mount version of the SA 21/4 but made an adapter ring for the ltm version.
It's very easy to see a small screw on the ring which fixes the lens body to the ring."

Clear as mud, right?