Bersa pistols are manufactured in Argentine by the Bersa S.A. company. Thunder pistols are available, in several different versions. The Thunder-380 pistols are of simple blowback design, while more powerful Thunder-9, Thunder-40 and Thunder-45 pistols are of locked breech design. Thunder series pistols are relatively compact and handy, yet they offer significant capacity with major pistol calibers, combined with good, fully ambidextrous ergonomics. Bersa pistols also are relatively inexpensive and offer decent reliability, making them good personal defense firearms. The only differences between Thunder and Thunder-mini pistols (which also sold as Thunder Ultra-Compact) are size and magazine capacity. The Ultra-Compact .45 pistols are roughly intermediate in size between standard and mini pistols, and, unlike smaller caliber brothers, they have a single stack magazine.
Bersa Thunder 9 pistols are standard issue pistols for the Argentinean Federal Police and the Buenos Aires Province Police.
Bersa Thunder-9, Thunder-40 and Thunder-45 pistols are locked breech, short recoil operated firearms of Browning type. barrel is locked to slide by single large lug, which engages the ejection port in the slide. The unlocking is caused by the cam-shaped underbarrel extension. Trigger is of double action type, with exposed hammer and ambidextrous frame mounted safety, which decocks the hammer when engaged, then locks the slide and sear. The action also features a firing pin safety, which blocks the firing pin until the trigger is pressed. The slide release lever also is ambidextrous, and the magazine release button can be easily mounted on the either side of the grip. magazines of the 9mm and .40SW versions are of double stack type, .45 caliber magazines are single stack. Sights are fixed, with front sight integral to the slide and rear dovetailed to the frame. Latest production pistols also feature an integral key lock, located above the trigger on the left side of the frame, as well as accessory laser / light rail on the frame below the barrel.