It's a very common misconception that it's legal to own/keep a gun (after having done military service) but not being able to get/keep ammunition.

According to this video you can't keep preciously-lent ammunition from the military. But you can for sure buy your own.

https://youtu.be/L00Pajw4NoY

As to why people don't use it or aren't scared, I guess they just aren't as wild...