[smokingfrog]

100 round "drum magazines" are available, but they're expensive, often not very reliable, and hanging all that extra weight from your rifle is going to make it less maneuverable. In this case, it's probably a good thing the shooter used one.

[Kickass Conservative]

I saw a picture of the AR he used posted here earlier.

It didn’t have a drum magazine. Looked like a typical 30 round to me. I think some Lib “Journalist” not using the brains God gave him, made it up for dramatic effect.

[jimbobfoster]

There are 100 round magazines available for rifles other than the AR15, but I would personally not use a magazine over 30 rounds. If I wanted dependability probably 20 rounds or less. Because of the weight, 10 rounds is good in a .308.