With Christmas fast approaching you may be thinking of getting that special person a firearm for a Christmas present, which can be done legally, even to someone under 18, and 18 to 21 years old, even in Florida.
Under Federal law you cannot sell or give a firearm to a person under 18 without parental permission. And you must have that permission in writing! So if your trying to give a firearm to your 16 year old niece or nephew for instance, get written permission from the parents to do so. The Federal law that applies is:
18 U.S.C. 922(x) (x)(1) It shall be unlawful for a person to sell, deliver, or otherwise transfer to a person who the transferor knows or has reasonable cause to believe is a juvenile— (A) a handgun; or (B) ammunition that is suitable for use only in a handgun. (2) It shall be unlawful for any person who is a juvenile to knowingly possess— (A) a handgun; or (B) ammunition that is suitable for use only in a handgun.
But that section goes on to list the exception being with written permission (among a few other exceptions). Florida law (Check your states laws for any difference) does not prohibit the private sale or gifting of a firearm to anyone who is not Federally prohibited if you follow the above for anyone under 18. Over 18 you can gift directly to the person, even in Florida as possession by anyone under 21 is not prohibited, only buying from a licensed dealer (some think it includes private sales, that has yet to be officially determined, F.S.S. 790.065 (13)) is prohibited.
But the generally accepted rule is that you may buy a firearm and gift it to someone as long as they are an adult, or Juvenile with written permission from the parents (not legally prohibited by State or Federal laws).