The Beretta 92

The Beretta 92 (also Beretta 96 and Beretta 98) is a series of semi-automatic pistols designed and manufactured by Beretta of Italy. The model 92 was designed in 1972 and production of many variants in different calibers continues today. The United States Armed Forces replaced the Model 1911A1 .45 ACP pistol in 1985 with the military spec Beretta 92F, the M9.
Although only 5,000 copies of the original design were manufactured from 1975 to 1976, the design is currently produced in four different configurations (FS, G, D and DS) and four calibers:
92 series in 9×19mm Parabellum
96 series in .40 S&W
98 series in 9×21mm IMI
98 and 99 series in 7.65mm Luger

History
The Beretta 92 pistol evolved from earlier Beretta designs, most notably the M1922 and M1951. From the M1922 comes the open slide design, while the alloy frame and locking block barrel (originally from Walther P38) were first used in the M1951. The grip angle and the front sight integrated with the slide were also common to earlier Beretta pistols. Perhaps the Model 92's two most important advanced design features appeared on its immediate predecessor, the 1974 .380 caliber Model 84. These improvements both involved the magazine, which featured direct feed, that is, there was no feed ramp between the magazine and the chamber (a Beretta innovation in pistols), and the magazine was a "double-stacked" high capacity design - a feature originally introduced in 1935 on the 9mm FN/Browning "Hi-Power".
Beretta modified the model 92SB slightly to create the 92SB-F (the "F" added to denote entry of the model in U.S. Government federal testing) and, later, the 92G for French Government testing, by making the following changes:
Design of all the parts to make them 100% interchangeable to simplify maintenance for large government organizations.
Modified the front of the trigger guard so that one could use finger support for easier aiming.
Recurved the forward base of the grip to aid aiming.
Hard chromed the barrel bore to protect it from corrosion and to reduce wear.
New surface coating on the slide called Bruniton, which allegedly provides better corrosion resistance than the previous plain blued finish.

Design
The Beretta 92's open slide design ensures smooth feeding and ejection of ammunition and allows easy clearing of obstructions. The hard-chromed barrel bore reduces barrel wear and protects it from corrosion. The falling locking block design provides good accuracy and operability with suppressors due to the in-line travel of the barrel. This is in contrast to the complex travel of Browning designed barrels. The magazine release button is reversible with simple field tools. Reversing the magazine release makes left-handed operation much easier.
Increasingly, it has become popular to reduce handgun weight and cost and increase corrosion resistance by using polymers. Starting around the year 2000, Beretta began replacing some parts with polymer and polymer coated metal. Polymer parts include the recoil spring guide rod which is now also fluted, magazine release button, magazine floor plate, magazine follower and the mainspring cap/lanyard loop. Polymer coated metal parts include the safety levers, trigger, trigger bar, slide lock/release and disassembly latch.
The 92 also spawned several variants of similar internal design. The Beretta 90two is a full-size variant of the 92-series with a redesigned slide and a redesigned aluminum frame with an internal recoil buffer, user changeable monogrips and an accessory rail.