Handgun

Handguns (also known as Pistols, Twin Pistols or Dual Pistols) are Lara Croft's default weapons and reliable companions in the Tomb Raider series and her default weapons in the most of the games. .

Tomb Raider - Tomb Raider Chronicles
Lara carries her dual pistols in all the games from Tomb Raider to Tomb Raider: Chronicles, n the original Series, with the exception of the Ireland and VCI Parts in Chronicles, the first two levels of Tomb Raider: The Last Revelation where she was only 16 at the time. The Pistols are modeled after the Browning Hi-Power.

Lara has unlimited ammo for these and will always carry two of them. They are not very effective, but most of the mortal opponents, except the skeletons and the mummies in The Last Revelation, can be killed with them. If you run and jump around a lot and circle your opponents they will suffice most of the time, even against a bigger opponent like the demigods or the T-Rex.

Angel of Darkness
While Angel of Darkness does not feature the signature Dual Pistols, it features many different models of pistol: the Vector R-35 (Heckler & Koch USP Match .45); M-V9 (Colt 1911 chambered in 9mm); Scorpion-X (Glock 17); Desert Ranger (IMI Desert Eagle Mark VII) and Rigg 09 (Ruger P08). There is also Kurtis's Boran X, which appears to be a customized Browning HP pistol.

Tomb Raider: Anniversary
In Tomb Raider: Anniversary, Lara uses Colt Mark IV 1911 pistols, apparently chambered for .357-caliber ammo (.357 can be seen stamped on the side in some cutscenes, notably when fighting the T-Rex). They feature twenty round magazines, and must be reloaded, but have unlimited ammo.

To reload, the aim button must be held and then the action button must be pressed.

Tomb Raider: Legend
Lara's pistols turn to Heckler & Koch USP Match pistols (appearing as RPG Mach-5) with silver slides and black frames. Several upgrades can be unlocked for them in game, including increased magazine size and damage.

Tomb Raider: Underworld
Dual pistols are the same as in Tomb Raider: Legend, Heckler & Koch USP Match pistols (appearing as RPG Mach-5) with silver slides and black frames.

Lara Croft and the Guardian of Light
The Dual Pistols are the first weapons the player uses aside from the Spear and Remote Mine, and therefor are the first weapons that appear in the players inventory. They are the weakest of all the weapons found in Lara Croft and the Guardian Of Light, however, they also happen to be the only weapons in the players inventory (not including the Spear or Remote Mine) that don't drain from the Ammo pool. This makes them incredibly useful during times where you may unexpectedly run out of ammunition for you're primary gun. It's a good idea to keep the dual pistols assigned to the D-pad, so that you always have them as backup.

Lara Croft and the Temple of Osiris
To be added...

Tomb Raider (2013)
Lara again uses several pistols, although only one of these will be in her inventory at the time: The Semi-automatic pistol (Beretta 92SB chambered in 9mm, upgraded to an M93R when the "burst fire" mod is added); Tactical pistol (Remington 1911 R1 Enhanced, chambered in .45 ACP) and Magnum Pistol. The Tactical Pistol Lara uses is one of a matching set, that belonged to Conrad Roth, who Dual Weilded them. He passed the pistols onto Lara when he died. Lara uses both pistols to kill Mathias.

Upgrades
Several upgrades and attachments, are available, they must be made use salvaged materials.

Rise of the Tomb Raider
Lara will have access to several pistols. She still has one of Roth's Tactical Pistols (Which is now simply the "Semi-Automatic Pistol"), it sports a new muzzle brake, and several new and returning upgrades. She also acquires a revolver whilst in Siberia.

Trivia

 * Oddly, when Roth has the Tactical Pistols, they have all upgrades, but they are stripped away when Lara acquires them, until they are made by the player.
 * Being naturally ambidextrous is somewhat rare, with only one out of every one hundred people being naturally ambidextrous.
 * Despite not appearing in the final game. Promotional material for Angel of Drakness features Lara using them. She also carries two pistols no matter what.

Gallery
Dual Pistols