I'm a Policer Officer in need of a life on the line shotgun. I bought a used 121 M1 back in the 80's. pulled it out of my gun safe cleaned it, took it to the range and it fired like a band new shotgun perfect. I was hope to update and use it for duty, but I could not find any parts on-line. A pistol grip stock and up to date fore-arm would be great if I could get one that will work. Any info would be helpful for me.