Out of curiousity, I looked up the Mars last nite in "Textbook of Automatic Pistols." I was going to copy the text verbatim for you but it turned out to be around 6 or 7 pp of small print. Basically, what I remembered was true; there was a .360/9mm and a 45 in both long and short persuasions. The 360/9mm put a 156 gr projo out at a scorching 1,650 fps and the 45 long was 220 @ 1,200 fps. This was before 1906, mind you!
The Mars was based on patents filed betw 1895 and 1905 and worked on the long recoil principle similar to the Frommer STOP with some differences. The locking was with a breechbolt with four symetrically opposed locking lugs 90 degrees apart. The bbl recoiled three inches, then moved forward 1/4 inch w/ the bolt and stopped again. This allowed the hammer which was cocked 15 deg past full cock to bear down on the tail of a carrier which had grasped the next ctg and pulled it backwards out of the mag during the recoil stroke. Whereupon the bbl returned forward under the influence of its return springs and allowing the carrier to rise from underneath. All the foregoing took place in the instant of firing and that is where the automatic action stopped until the trigger was released which tripped the bolt to go forward, chamber the next round and prepare for the next shot.
The Mars were made individually by Birmingham gunsmiths and had the fit and finish of best grade British shotguns of the day, in other words, impeccable. Names like Holland & Holland, Purdey, and Westley Richards spring to mind. There was also a 8.5mm Mars listed but Wilson had never seen one nor was able to find a catalog. Even back in the '30s he couldn't determine a price since they had never been commercially marketed to any extent. He did state that the 360 was singularly unpleasant to shoot. About 3X as powerful as Colt's Super 38, methinks.