I guess the possible magazine sizes play a role here. I can't imagine a hunting rifle with a 100 round mag. And aren't most of them bolt action, that is, not even semi-automatic?
The thing is, there's no clearly defined set of characteristics that makes a firearm "military", "hunting", "sniper" or any other purpose. There are bolt-action rifles that take 20-round detachable magazines[0] and semi-automatics that only hold 4[1]. Incidentally, putting some different accessories on that same rifle makes it look like a military weapon[2].
The primary functional difference between guns labeled "military-style" or "assault" and "sporting" or "hunting" is a detachable magazine with larger capacity. One might think that regulating those would be an effective means of mitigating the impact of criminal acts with guns, but that was tried and did not appear to have the desired effect[3].
The lunatic who attacked the school was not trained, but was also attacking cornered, defenseless children at short range. Practically any firearm would have been used in this attack to equivalent effect.
As far as I'm concerned, the only thing that might have stopped this (once it started) would have been a police officer at the school or an armed teacher (http://en.wikipedia.org/wiki/Pearl_High_School_shooting). We might have better been able to prevent the shooting from taking place at all with better mental health care. They weren't even his guns, so gun control that inspects the purchaser would not have worked.
