State police officers conducted the Thursday raid at the company's Oberndorf corporate headquarters in Baden-Württemberg, searching the building and several nearby private homes for information about bribes the company is alleged to have paid to Mexican officials.
Those bribes are said to have resulted in weapons contracts with authorities in Mexico.
The company, which produces many of the world's most popular small arms for police and military use, has been dogged by investigations into its Mexican operations for years.
Last December police searched its headquarters after it was accused of bribery and selling arms to Mexican states where serious human rights abuses had taken place.
It later said it never sold weapons directly to Mexican states, but rather directly to Mexico's federal government.
This summer it emerged that rebels in Libya were using Heckler & Koch weapons, although the company denied selling weapons to anyone in the country. German prosecutors have since launched an investigation.
Although it has not yet responded directly to Thursday's raid, Heckler and Koch has previously insisted all of its operations in Mexico were legal.
In its last statement on the matter, dated March 10, it said the company “never paid a cent of bribe money to Mexican officials to support the sales of the products. The allegation of bribery has been launched by a group of persons including a former H&K employee who is now working for a competing company.”
Heckler & Koch has been selling weapons to the Mexican government for more than 20 years.