AMT Lightning cal .22LR Pistol

I recently purchased a used Arcadia Machine and Tool (AMT) Lightning .22LR cal pistol and would appreciate information on these pistols. It is made of stainless steel, has a bull barrel, and is almost an exact copy of a Ruger Mark II. Other than for minor differences (e.g., trigger guard, flat sides on the receiver, machined scope mounting grooves) I can't tell the difference between the two. The owner's manual schematic is identical to that shown in the owner's manual of my Mark II. I understand that the Lightning was only made between 1984 and 1987. Are these two pistols identical? Are parts interchangeable between the two? Was the Lightning made under license from Ruger or made by Ruger for AMT? If not made by, or under license from, Ruger, did AMT produce them in violation of patent rights? Why were they manufactured for such a short period of time?My AMT Lightning is a beautiful pistol, very well constructed and shoots extremely well. It was purchased from a friend, the original owner, who due to the increasingly restrictive (and expensive) gun laws in New York City was forced to dispose of his firearms. While I have not been able to find out much about the Lightning pistol, I understand that AMT also produced a stainless steel twin of the Ruger 10/22 rifle, also called Lightning. Is the history of this firearm similar to that of the pistol?Thank you for your help in this matter.