Richard Jefferson Says Ja Morant Gun Video Won't Tank NBA Career

No, Ja Morant is not throwing away his NBA career ... at least, that's according to Richard Jefferson, who tells TMZ Sports the star's latest lapse in judgment is simply a young man "making mistakes in front of the public eye."

The former NBA champ made the comments to us out at LAX on Monday -- just two days after Morant filmed himself brandishing a gun while out at what appeared to be a Colorado strip club.

Many believe the 23-year-old is tanking his own career -- as he's now not only under police investigation over the footage, but he's also been booted from his Grizzlies team for the time being.

Jefferson, though, said he doesn't have any concerns this could derail the superstar's track in the Association ... telling us he's confident Morant will learn and grow from the fallout with relative ease.

"Him and his family are good people," Jefferson said, before adding, "I believe in him. I believe that he'll kind of turn things on. And, look, we've seen men come through worse and come out on the other side."

Morant -- who was also accused of flashing a gun at a high school basketball player during an altercation with the teenager at his home last summer -- vowed on Saturday to seek out help.