Yes, drum mags - either you love them or hate them. Personally I love them, probably because I've had nothing but good results. I recently picked up a GSG 110 round drum for the 10/22. I've run over 1000 rounds through it without one failure - I'm thinking this is nothing short of amazing knowing the untrustworthy nature of cheap Rimfire rounds. It was getting a little old changing out and reloading the 10 round mags at the range over and over and over. The drum was 50 bucks. Cheap and really fun to just keep pulling the trigger. I've also had no issue with a black dog 50 round drum for my wife's M&P 15/22, also no failures after thousands of rounds. I have to give a positive thumbs up for both of these drums.
I don't have one, but have read consistently good reviews on the GSG drum mag for the 10/22.
I don't have one either, but it seems like it would be impossible to get one's support elbow far enough underneath the rifle.
In known distance shooting it is more important that ones elbow be in the same place than that it be under the rifle. If you were to look at the US AMU International Shooting Manual, you would see the instruction that your arm should be beside the rifle, not underneath. Dick Whiting, well known High Power coach and shooter, instructs his students to get their elbow as close to underneath as conditions allow and so as not to cause undue pain to the support shoulder.
I have coached several shooters who were in extreme pain because they were told that their elbow had to be under the rifle during instruction. It doesn't. But it should be in the same spot, throughout the string.
Hate em.
Too much unnecessary goin' on!