In 1983, the LUSA-A2 SMG was developed by INDEP Industries of Portugal who, at the time, was manufacturing under license from H&K, the HK21 and the HK G3. Improvements and modifications were a continuing process, culminating in 1992, and with a development cost of 2.5 million dollars. The weapons are now used by the Portuguese and three other European countries.

The Name LUSA is derived from Lusitania, which is present day Portugal. Although designed as a military weapon, the LUSA-A2 is well-suited for law enforcement. The trigger group is nearly identical to that of the H&K MP-5 and the barrel is quick-change, similar to the UZI. The bolt and carrier are one unit.

In 2004, INDEP sold all dies, tooling, fixtures and manufacturing rights to group of well established names in the firearms industry. Stan Andrewski, owner of Stan's Gunsmithing for over 30 years in New Hampshire, Jerry Prasser, owner of Recon Ordnance for 29 years in Wisconsin, and Ralph Demicco, owner of Riley's Gun Shop. The company was named LUSA USA.

The LUSA has been approved by the Bureau of Alcohol, Tobacco, Firearms, and Explosives and is for sale as a semi-automatic firearm to the civilian market. The amount of U.S. manufactured compliant parts has met government requirements.

The selective-fire model is available to Law Enforcement and government agencies, both foreign and domestic. Class III dealers can obtain a LUSA-A2 for demonstration purposes with the required LE demonstration letter.

Sight rails, folding stocks, and non-retractable stocks are now available. Suppressors are available for the LUSA A2.