In the US, only 37 companies (~2% of the industry) produced 75% of all domestically made firearms. These companies (shown in infographic above) also exported guns to other countries worldwide. The gun industry had an economic impact of $32 billion, a major portion of which was controlled by these 37 manufacturers.
Data on the US firearms industry is difficult to obtain. Used here is the latest and most reliable source, the 2013 SAS (Small Arms Survey) report, The US Firearms Industry: Production and Supply by Jurgen Brauer, which covers 1986-2010. SAS combines data from online ATF (Alcohol, Tobacco, Firearms and Explosives) reports from 1998-2010 with data for 1986-1998 obtained via Freedom of Information Act requests to the ATF.
Due to the US Trade Secrets Act, manufacturers delay reporting data to the ATF by one to two years. Figures exclude what is produced for the military, but include guns manufactured for US law enforcement, US civilians and international export. SAS verifies data from manufacturers and estimates underreporting at ~1%. SAS obtains additional data from the FBI, customs and other sources. Data in the 2013 SAS report begins in 1986, after the passage of the ferderal Firearms Owners Protection Act. This act limited the power of the ATF to inspect firearms dealers and prohibited the creation of a national firearm registry; it also banned the sale of machine guns to civilians.