ps90

Posted here as I figured more in this section would have knowledge on the subject. Apologies if its in the wrong catagory. Q- Can you tell what gen or trigger pack comes in a PS90 by the serial number alone? If not what maybe good signs its not the 1st or 2nd gen...all without field stripping it...

Purchased a used ps90 and it came with this optic mount attached. Can anyone tell me what kind of mount it is and what optic it is designed for?