TMZ has learned the NYPD paid a visit to Plaxico Burress' house this afternoon, and retrieved what appears to be the gun that triggered this whole mess.

The cops arrived with a manila envelope, but a search warrant was NOT inside.

We're told Burress was not there, but authorized someone inside his home to give police the gun that apparently fell down his leg at a nightclub Friday night and accidentally fired.

It would appear reports that he dumped the gun somewhere in New Jersey are not accurate. As we reported, Burress will surrender tomorrow, and plead not guilty to a felony weapon charge.