Chris Brown -- Bodyguard Busted for a Concealed Weapon

Chris Brown was being well-protected by a bodyguard armed with a loaded Glock ... problem is, it's illegal for him to carry it in California, so he got busted for felony illegal gun possession.

Law enforcement tells us, Clay Lewis claimed he was on guard as Chris partied Sunday night at Penthouse nightclub in Hollywood. Cops strolled by Lewis' car, saw a weed grinder and rolling papers in the front seat, so police asked if they could search his car. Lewis obliged.

It's puzzling why Lewis said yes, because he had a loaded Glock in the trunk. Turns out Lewis had a concealed weapons permit in Florida, but did not have one in California. Thus, he was busted.

Interesting fact ... law enforcement tells us they were on heightened alert outside Penthouse specifically because Brown was inside, and they had more officers there than usual.