An ex-con gang member was caught red-handed with a loaded gun in Brooklyn when cops busted him for sneaking into the subway system without paying, authorities said. 

Isaac Foster, 35, a member of the G-Stone Crips, “manipulated the turnstile” to enter the Kingston–Throop Avenues station in Bedford-Stuyvesant around 9:40 a.m. Wednesday, cops and police sources said. 

Officers inside the station stopped him and found that he was carrying a loaded Ruger LCP .380 defaced firearm, they said. 

Foster, who lives in Crown Heights, was arrested at the scene and charged with multiple counts of criminal possession of a weapon, willful defacement of a machine gun/weapon, and theft of service, the NYPD said. 

He was ordered held on $25,000 bail or $50,000 bond during his arraignment, records show. 

Foster served time in state prison on a second-degree assault conviction between 2005 and 2008, according to state correction records. 

He has also previously been arrested for criminal possession of a weapon, grand larceny and petit larceny, police said. 

According to sources, Foster was injured in a shooting in Brooklyn in 2019. 

The NYPD on Thursday tweeted a photo of the defaced gun, as well as two Transit District 33 cops involved in the arrest. 

“A gang member with a history of gun arrests was nabbed yesterday by
@NYPDTransit cops after he was observed beating the subway fare & found in possession of this defaced firearm,” the tweet said. “Your officers who answered the call to service are committed to making this city safer.”