I don't know, why don't you tell us, how many don't store their guns properly? Please also tell us how often legal gun owners have used their weapons in self defense in the last 10 years? I'm going to guess it's rare on both accounts. But you're welcome to prove me wrong.
But back to the original topic, how does preventing legal gun owners from owning those long guns make things safer when it's neither legal gun owners committing gun crimes, nor using those long guns in the first place?
If police were allowed spot-checks, maybe we'd have an exact answer but based on comments from alleged gun owners on here, many refuse to follow the law.
I have absolutely no problem with actual 'legal gun owners', hunting, or target shooting but most of the complaints about gun laws are simply NRA spillovers from people who don't understand that US and Canadian gun laws are extremely different, even down to the function guns play.
As an analogy, I am happy that sex work is legal in Canada and purchasing it is defacto legal but I fully understand why streetwalkers and sex in public aren't.