"What's illegal? Buying bullets for semi automatic weapons?"
Not by itself but if you're buying them with the intention "to shoot up your class-mates" then it becomes illegal, and that's what your post was referring to, not just a random person buying some ammo.
"They're has to a balance" - the best overall 'balance' is that nobody has guns at all"
I respect that we have different beliefs on this, and actually if you can think of a way to ensure that nobody has any guns at all and can guarantee it I would support your stance on guns.
"armed police when you need them - the rest, No. Ciivlians in a democratic society not at war - no guns - is good.
And if you need armed police to be here within seconds, but they won't make it to your location for 4 minutes?