Police allege the ring peddled weapons in two ways: by obtaining guns in the United States and smuggling them into Canada, or by purchasing them legally in Quebec and reselling them without serial numbers.
Provincial police spokeswoman Martine Asselin said the weapons were sold from a base of operations, on the reserve, to a wide-ranging clientele.
About 100 provincial police and Kahnawake Mohawk peacekeepers took part in a series of pre-dawn raids early Tuesday, after a four-month investigation.
Police say eight people were arrested and charged with weapons trafficking, possession of prohibited weapons and conspiracy. Seven were from the reserve and another man was from nearby Chateauguay.
Police allegedly seized 42 guns including some that are prohibited and others that had been illegally modified. Ammunition and other explosives were also allegedly seized, in addition to $22,000 in cash and some drugs.