Travis Hunter knows how to bust through a secondary on the gridiron ... but he watched cops pull off a real bust during a recent ride-along in Jacksonville.

The Jaguars star rode shotgun with Sheriff T.K. Waters for a YouTube video published earlier this week ... and the two-way stud hopped out of the car at one stop to chat about a developing situation.

While Travis isn't playing in NFL games that count just yet, these cops down in the Sunshine State don't take days off ... and they show Sheriff Waters a bag full of drugs they say they recovered during a traffic stop.

Watch the clip for yourself ... cops are alleging they found just about every drug under the sun -- weed, meth, what they say looks like cocaine, and even fentanyl -- while Travis listens in stunned silence.

As the officers walk off to deal with the alleged drug possessor, Travis says, "They done caught a kingpin," ... before following it up by telling kids not to mess with drugs.

Travis is heading into his second season for the Jags ... having appeared in just 7 games during his rookie campaign.

Football might be good for now ... but it seems the star's got a bright future on the force if he wants to pursue it!