Or this one--- 1 of 10, SIG 550, 50-round, experimental, metal drum magazine.
Tony
eh, that you'd be too difficult to make..........and it wouldn't be some laughable low-capacity 50 round drum. but 120 round drum.
first take a 120 round AR drum and a SIG mag, cut off the AR feed tower, make the SIG mag single feed, position it over drum opening and welded it in place......then you'll have a one of kind drum that no one has not even SIG