A Long Island plumber was busted after state troopers found 41 guns — including 27 high-powered assault rifles — stashed at his home.

Bing Sang, 40, was arrested Dec. 11 when state troopers searched his Amityville pad and confiscated the arms cache.

Cops said Sang bought most of the weapons — including tommy guns and rifles — for nearly $30,000 over the past five months.

But the suspect was charged with felony gun possession because three of the weapons are illegal in New York.