IMFDB makes me very happy.

But yeah, a lot of the regulations are very vague and weird, simply because of how hot a political issue it is.

Australia has a reputation for having an effective gun control policy, but The Source makes me wonder if that reputation is deserved.

I'm inclined to agree. If you look at their murder rates pre-1996 and post-, there doesn't seem to be a major change. One of the things that you have to be careful about is studies that look at whether gun homicides go down as opposed to just homicides in general. In other words, you can't say that stricter gun controls reduce homicide if people just start killing each other with something else. I'll also note this study (PDF) that discusses gun ownership rates and homicide rates in various countries.

I always thought he was just whacking the magazine to make sure the cartridges were lined up or something, like a pack of cigarettes.

Nope. There's a famous scene from Apocalypse Now where a guy in a helicopter does this on his helmet, but I don't think it's actually necessary.