There are maybe ten of the Dual Feed guns that either I have built, or privately built where I made the special components available to good friends who were part of helping me get started in the business. I never offered a Dual Feed conversion kit for general sale, as there is no money to be made that way. But the original owner of this gun helped me out a lot, as have a couple of others that earned much gratitude for their support. I have parts to build 10-15 more, eventually. But I am not planning on doing any for a while, with other projects taking priority. There are your M37s out there, but these Dual Feed "hybrid" guns are unique. And Len, your 1917A1 Dual Feed is the only other one built besides my personal one, and the only one that is blued.If I did not already have one of Lucky's earliest dual-feed 1917A1's,I'd be looking to buy this 1919a4. Good question though...how many dual-feeds are out there...1917A1's and 1919A4's....?