Beretta

Beretta M9 is a standard pistol that is free upon death whether its from an SCP, player, or suicide. It is only available since your first death after you join the game.

History
The Beretta is an American pistol that shoots the 9x19 mm Parabellum cartridge and in the army was a standard issued gun. Its Italian original is Beretta 92F that is more complex and takes more time to produce. The gun was used in the army since 1985 and since 2017 it is being replaced by M17 and M18 pistols which are designed on the basis of a German SIG Sauer P320.

Pros

 * You don't need to go to armory to get it.
 * It has good recoil and good range.
 * It has normal ammo storage.

Cons

 * It deals lacking damage, so it's only efficient during your spawn forcefield is active.
 * It is also not available until your first in-game death.

With Beretta
Beretta is available since your first death, so it can be most effective while the spawn forcefield is active. Try maintaining range with the player against you as the recoil can let you do that. You have normal ammo storage, but lacking damage, so you need to land at least half of the shots on a player. Anyway it is not a beginner weapon.

Against Beretta
Wait until the spawn forcefield runs out to lower the effectiveness of this sidearm. Get as close as possible because it has good recoil (that means no stray bullets will hit you). M9 has lacking damage - use it to your advantage. Use close range weapons.

Trivia

 * Beretta M9 has three modifications: M9A1, M9A2 and M9A3.
 * Anyway, in-game Beretta does not really match to any of these.
 * It is bigger than the real model.
 * Its ammo capacity also does not match to the real one - 12 rounds in the game vs 15 or 17 (M9A3) rounds in the real life.
 * Strange enough, Beretta M9A1 in the "SCP rBreach" game also has the same amount of bullets in one mag.