Bingo Airsoftworks posted a preview of their lates project --- converting a RAP4 M1919 to use the PolarStar Airsoft Conversion Engine... "RAP4 M1919 PolarStar Fusion Engine conversion. Extensive retrofitting requiring the removal of all the paintball internals (except for the trigger) and rebuilding for the Fusion Engine. Custom 3D printed hopup block and Fusion Engine mounts, as well as the box mag cutout coverups and BB feed mechanism. I'll be doing outdoor test firing and video soon. Full writeup following."