2 Chainz -- I Was Shot At ... BULLET FRAGMENTS IN MY HAIR

2 Chainz is lucky to be alive ... and in his first interview since he was robbed at gunpoint, not only does he say he was he shot at, he says he ended up with bullet fragments IN HIS HAIR.

The rapper went on Atlanta radio station Hot 107.9 to give a play-by-play of the crazy incident in which two gunmen opened fire on Chainz and his crew in San Francisco on Sunday.

Chainz describes the moment he saw one of the gunmen approaching, explaining, "I saw the gun before I saw him ... It was so heavy he couldn't really hold it ... the gun was so big, that's what made me take off running."

You can listen to the rapper's entire interview above and relive the entire incident below.