Re: A.R. 10 Drums
100rds loaded in 30 magazines weighs less than a beta cmag loaded with 100rds for the AR-15. Plus it's bulky and takes up way more space. Offhand it sucks to hold. I can only imagine that on the .308 this would be even worse.
They're fun and that's it. Even in a competition setting they wouldn't give you a real advantage.
Beta made a 7.62 version of their drum and one is M14 compatible. The Armalite AR-10 mag started out as an M14 mag, so I could easily see a new tower being made from an AR-10 mag or modifying the M14 tower on the beta mag to fit the AR-10.