1) Since you say that anyone could manufacture a TSMG when the patents expired, could you provide the date these patents expired? Doug Richardson has a book on the Thompson patents. I suggest you read that if you need actual date information for specific patents. I believe there is also another book on Thompson patents. I am thinking Don Thomas is the author but I am not 100% sure. Suffice to say, once patent protection expired, anyone was/is free to manufacture a Thompson. 2) If AOC did not have a contract with Colt to exclusively make the TSMG back in 1921, could you provide the other firearm manufacturers that AOC contracted with simultaneously? Could you please show me where in the Auto-Ordnance/Colt's contract where Auto-Ordnance agreed Colt's would be the exclusive manufacturer of the Thompson Submachine Gun for any period of time. Not that it really mattered, the initial lot of 15,000 guns took nearly 20 years to sell. 3) If as you say Colt was a subcontractor of AOC, could you provide information of AOC actually making the TSMG during the period Colt was making them? Contractor or subcontractor, there is no need to argue semantics. Colt's was paid to perform a service for Auto-Ordnance. And they did. 4) Could you provide the page in TUTB where Hill or any contributing author provides a photo of a Chasan TSMG? I could but I am going to let you find it. From the above questions, you need to read the works of original researchers.