Aaron Carter is adding to his home arsenal … hitting up a pawn shop to purchase 2 guns and a bunch of ammunition.

The singer dropped by Rick's Pawn Shop Tuesday in Lancaster, CA … and we're told Aaron bought a handgun and a rifle, plus 300 rounds of hollow tip bullets.

Looks like Aaron is dead set on starting his own gun collection after inheriting a massive cache of weapons from his father. Aaron got his gun license less than 2 weeks ago, and he immediately bought a 9mm handgun and 2 assault rifles.

After Tuesday's purchase, Aaron owns at least 5 firearms — still a long way to go to catch up to the 500 guns he says his pops passed down to him.

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We broke the story … Aaron told us last week owning assault weapons is a necessity, because his dad taught him to protect himself and his family by any means necessary. Aaron also said his mental stability is "infinite" — despite loved ones being concerned about his mental health.

BTW … Aaron had his background check flagged two years ago when he tried toRead More – Source