i modified the saurekrauet v2 hing mount t betterfit the 1913 rail on the back of our remixed dear22 and decided to put a buffer tube on it since we didnt include the buffer tube version of the lower in our release. included is a step file that has all of the parts for the sauerkraut hinge mount assembly. if you open the 3mf file it will load in the orientation that has provided the best results for me. mine is printed in pa6-gf with 5 walls and 99% gyroid infill. enjoy