The FA Modelo 03 rifle was an individual firearm of bullpup design developed by Nelmo Suzano at his own-funded company, LAPA - LABORATORIO DE PESQUISA DE ARMAMENTO AUTOMATICO Sc/Ltda, in Rio de Janeiro, Brazil. The name stands for the Portuguese "Fuzil de Assalto Modelo 03", or "Model 3 Assault Rifle", whilst the name of the company stands for "Automatic Armaments Development Laboratory, LTD.".
Development and manufacture of this weapon lasted between 1978 and 1983, along with two more models (a 9 m/m sub-machinegun and a .22 - Long Rifle sub-carbine of conventional design) with the purpose to obtain both domestic and export Military and LE sales. The FA Modelo 03 is the only firearm in bullpup design to have been experimented by LAPA.
Basically, the FA Modelo 03 was nothing special in its mechanical conception, just a selective-fire assault rifle based on a conventional piston-operated system with rotating bolt locking. Its most interesting feature was the total lack of a manual safety. The fire selector switch, located on the left side of the weapon, had three positions: two for the fire mode (Semi-automatic fire or Full-automatic fire) and one to set the trigger to Double-Action. The rifle could thus be carried safely with loaded chamber and hammer in lowered position. This, in mind of the creator, worked effectively as a safety, since firing the rifle in such a situation would have called for a deliberately long and heavy trigger pull which could not happen by accident nor by stress; and it also ensured the impossibility of unwanted discharges by accidental hammer release due to any technical problem that a firearm could experience.
It is interesting to note that the first-shot double-action trigger is something seldom-experimented on full-automatic firearms of Military/LE issue. The only major experiment of a double-action trigger on a select-fire weapon was with the Italian SITES Spectre M4 sub-machinegun. It should be noted, anyway, that this system is blamed by gun experts and experienced shooters to induce too much self-confidence on operators, leading them to keep their finger on the trigger at all times even when the gun is not pointed at a target. While some military personnel consider this a good thing for readiness to fire especially in current military theatres of operation (like Afghanistan and Iraq), the practice of keeping the index finger on the trigger when the gun is not pointed at a target is always thoroughly disencouraged as one of fundamental rules of gun safety calls for "always keeping the finger off trigger until ready to fire".
Also, the LAPA FA Modelo 03 rifle featured a full plastic chassis/housing that protected the mechanisms from any external aggressive factor (such as mud, dust, water, etc.), and considerably decreased the overall weight of the weapon. The rifle was originally conceived to feed from proprietary clear plastic magazines, since then it was made to fit STANAG magazines to facilitate exports and usage in those countries which already had in service weapons that used such feeding systems (particularly, at the time, the M16 rifle). Calling the LAPA FA-03 a "5.56x45mm-NATO rifle" would be incorrect, as at the time of its introduction the current NATO standard 62-grain FN SS109 ammunition had not yet been launched. Having the barrel only an 1:12 pitch rifling (1 turn in 305 mm), the LAPA FA-03 could thus only fire the 5.56mm M193 variant (55-grain ball cartridge) as used by the US forces during the Vietnam war.
Unfortunately this also was the cause of its demise, because the Brazilian military and police personnel was at the time (and still mostly remains) used to heavy-weight firearms after years and years of issue of locally-manufactured clones of weapons such as the FN FAL battle rifle and the Madsen m/50 sub-machinegun. The members of the Brazilian Military that experimented the FA Modelo 03 and other LAPA firearms at the Marambaia Testing Ground in the early 1980s reportedly discarded all of them due to their "toyish" look and weight (all LAPA weapons shared the full plastic housing feature, this reduced weight but apparently didn't afflicted controllability on full-automatic fire).
When the FA Modelo 03 was first engineered, it also was a novelty because of its bullpup design, the only other firearms of such layout available on the market at the time being the French FA-MAS and the Austrian Steyr AUG. But when the FA Modelo 03 was ultimately offered for sales, all the marketplace that the world then had for such a firearm had already been taken by the AUG, which remains to date the most successful weapon of bull-pup design ever. Orders were null, both domestically and abroad, and LAPA folded shortly after 1983, with less than 500 FA Modelo 03 rifles manufactured overall, mostly still today kept in stock by Brazilian Police forces for SWAT-like teams use.