The New York City Police Departmentwas tipped off to the largest gun bust in city history through anaspiring Brooklyn rapper's Instagram posts.MatthewBest - who has released a couple mixtapes under the name Neno Best -was regularly posting photos and video of guns and wads of cash online,saying he was selling weapons out of his Ocean Hill recording studio.That led police to a multi-state gun trafficking ring that netted 254 firearms and 19 indictments.Initially the department wasinvestigating drug charges on Best after he started posting the photos.By wiretapping him, investigators were led to two men in the Carolinaswho were smuggling guns separately but using the same middleman in New York City.Walter Walker and Earl Campbellsourced guns from suppliers in their hometowns of Sanford, NorthCarolina and Rock Hill, South Carolina and sold them on the black marketin New York.Whenthe NYPD found out about the illegal business, they sent an undercoverofficer posing as a gun broker to buy the weapons off the two men.The smugglers would take pictures of the guns they were offering and send it to the undercover officer.Theywould then transport the guns into the city, using cheap Chinatownbuses to avoid attracting attention or having their bags checked bysecurity. Apparently thecity's stop-and-frisk policy was a concern for the smugglers. CommissionRay Kelly read from one wiretap where a gun distributor alluded to thecontroversial search: 'Yeah, I’m in Charlotte now, I can’t take them tomy town…we got like whatchamacallit, stop-and-frisk.'Thefares on these buses are about half that charged by Greyhound, which,unlike the Chinatown buses, requires identification for boarding.Walker met two times last year withthe middleman and the undercover officer at the rapper's Brooklynrecording studio to sell the undercover firearms, the indictment said.He also allegedly sold weapons to the undercover officer in April inManhattan.In January, Campbell's girlfriend transported a disassembled gun in a zebra-striped suitcase.Whenthey arrived in New York she proceeded to take the weapon parts out ofthe bag and assemble them in the back of a car watching a YouTubetutorial for guidance.When she couldn't figure out how to put the weapon together, the undercover cop bought the pieces anyway for $1,100.Walker and Campbell were arrestedearlier this month by local police in their home states, authoritiessaid. The names of their defense attorneys were not immediatelyavailable.New York has some of the nation's strictest gun-control measures and a mayor who has crusaded for tougher laws in other states.'There is no doubt that the seizure of these guns has saved lives,' Mayor Michael Bloomberg said at a news conference.