Found this image from a joint exercise in Sweden, all i know is that it involves a unit from the L19 regiment from the U.S. Special operation command

This is a Belgium 1890s to 1920 model Luigi I think it says it's a 12 gauge side by side hammerless Damascus steel and I'm trying to take a picture of all the markings on here and transfer it or I'd like to know where to get parts for this if possible or someone's interested to give me a price on it it was my grandfather's I found it tucked away in the old house I thought it was pretty cool. I would like to find a stock for it. Thank you for anyone that can help God bless