I've never seen one of those. I've approximated this pistol with my 4" 22/45 and a 6" suppressor but it's not as "cool" looking. These can be a very effective tool and with the right ammo both accurate and quiet.
The specimen I was familiar with was the High Standard HDM with integral baffle suppressor. It had been internally modified to allow the safety to lock the bolt closed. Actual safety was de-activated but the half cock allowed safe carry/handling with a loaded chamber.
Had one of those in my collection for many years but sold it recently. They were not very quiet to shoot. Suppressor technology has improved a lot since these were made. Not many around so they are very collectible if you can find one.
I heard about these back in the 70’s. Thanks for sharing this article! I bought a Mk ll in the early 80’s, and I shot it better than any .22 LR rifle. I still have it, but my eyesight has faded.
gramps