How do they go about enforcing such a silly law? And would they consider components to be assembled ammo?
Well the law is what it is.
I am sure some flaunt it, but then if you only have a gun for SD, you don't need hundreds in stock and if you go to the range you can buy some especially. That is their logic.
The only components restricted in a similar fashion are primers and the powder. 1000 of the former and 4 kg of the latter. So even if you had all of that and hundreds of bullets and cases, you couldn't, in theory, make up and store more than 100!!
I'm sure some flaunt the law and I've never heard of the police doing home stock checks, but if it is the law, I'll stick to it. With a 1000 round sports licence limit, I don't feel it restricts my shooting at all.