It is, because they get them after serving mandatory time in the military. So more or less every swiss man has a military grade weapon at home. Only in newer times the ammunition is stored in special houses in each community. Before, they had their ammo at home.

They're also rifles, not handguns - and it's handguns that are the problem in the US. Around 75-80% of firearm murders in the US are by handguns.