I now have several of these Black Dog drums and really like them... My .22 upper uses a modified Ciener kit that has become very picky. It ran great for thousnads and thousands of rounds but is not quite as cooperative at the moment. I have run several hundred rounds through some Nordic Component uppers with these drums with great sucess. I'll be picking one of those up as soon as possible.
I did find at the last USSA rifle match that it's possible to cause malfs with the BDM drum by careless or improper loading techniques. I had several failures on a single stage. When loading for the next stage, I discovered that I had gotten some rounds out of alignment by holding the winding tab too far down as I dropped the rounds in. By paying more attention to what I was doing from that point on, it worked perfectly.