Uh...no, you are the one that’s incorrect.
Federal law sets the age to purchase or possess a handgun at 18 years. There is no federal age limit on possessing a long gun.
18 states have enacted laws raising the minimum age to purchase/ possess a handgun at 21 years.
4 states have set the minimum age to purchase a long gun at 21 years. 1 state limits semi auto long gun purchases only to 21 and another limits long gun purchases to 21 if you do not have a hunter’s safety certificate.
State laws concerning the minimum age for simply possessing a long gun are more complicated. In most states the age is 18 however there are a few exceptions:
Hawaii & Illinois - 21
Washington state - 21 for semiauto long guns outside of private property.
D.C. - 18 with parental consent.
Alaska - 16 without parental consent.
Massachusetts - 15 with parental consent.
Minnesota - 14 with firearms safety certificate otherwise 16.
Lastly, handguns are not “more restricted” because they are “considered more for personal defense”. Handguns are more regulated because they are more concealable.