3d printed 50 beowulf magazine and firing 7.62x39 bca upper(works this time!)

I 3d printed a 50 beowulf magazine from fosscad. It worked! I do need to tweak the slot for magazine catch to hold the magazine in place. I also shoot the 7.62x39 ar47 upper from bear creek arsenal in this video. I shot some surplus ammo out of it and it