Minn. Stat. § 609.663: DISPLAY OF HANDGUN AMMUNITION.

It is a petty misdemeanor to display centerfire metallic-case handgun ammunition for sale to the public in a manner that makes the ammunition directly accessible to persons under the age of 18 years, other than employees or agents of the seller, unless the display is under observation of the seller or the seller's employee or agent, or the seller takes reasonable steps to exclude underage persons from the immediate vicinity of the display. Ammunition displayed in an enclosed display case or behind a counter is not directly accessible. This section does not apply to ammunition suitable for big game hunting.