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 signature dual pistols in all the games from Tomb Raider to Tomb Raider: Chronicles, in the original series, with the exception of the Ireland and VCI chapters in Chronicles, and the first two levels of Tomb Raider: The Last Revelation where she was only 16 at the time. The pistols for the first three games are modeled after the Browning Hi-Power, and the Colt M1911 for the inventory model in TLR and Chronicles.

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 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 in .45); M-V9 (Colt 1911A1 in 9mm); Scorpion-X (Glock 17); Desert Ranger (IMI Desert Eagle Mark VII) and Rigg 09 (Luger P08). There is also Kurtis's Boran X, which appears to be a customized Browning HP pistol.

The dual variants of the Vector-R35 and Scorpion X are still present and functional in-game, but weren't properly implemented due to cut content and time restraints. They can be accessed via a startup configuration utility or Action Replay for the PC and PS2 versions respectively.

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 20-round magazines and must be reloaded manually, 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 are Heckler & Koch USP Match pistols (noted in-game as the RGB Mach 5) with silver slides and black frames. Several upgrades can be unlocked for them in game through collecting enough rewards, including increased magazine size, targeting range and damage.

Tomb Raider: Underworld
Dual pistols are the same as in Tomb Raider: Legend, Heckler & Koch USP Match pistols (appearing as RGB Mach 5) with silver slides and black frames, albeit with Desert Eagle styled safety and Beretta 92's ejection port.

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 your 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 (IMI Desert Eagle Mark XIX, chambered in .50 AE). The tactical pistol Lara uses is one of a matching set that belonged to Conrad Roth, who dual wielded them. He passed the pistols onto Lara when he died. Lara uses both pistols to kill Mathias in the game's climax.

Upgrades
Several upgrades and attachments, are available, they must be made use salvaged materials. Finding all the extra handgun parts will replace the Tactical Pistol with the Magnum Pistol.

Rise of the Tomb Raider
Lara will have access to several pistols. She carries a gun that is the same model as Roth's old pistols, it sports a new muzzle brake, and several new and returning upgrades. She also acquires a revolver whilst in Siberia.

Handguns
Revolver: An older pistol balanced for variety of situations.

Semi-Auto Pistol: Standard issue pistol focused on rapid firing speed.

Accipiter Nox: Matte black semi-automatic pistol. Obtainable with Siberian Ranger DLC.

Rattlesnake: X-Box limited edition gun, obtainable only Between 10-30 Nov 2015.

Alternate Ammo
Hollow-point Rounds - Fragmenting pistol rounds that do increased damage. Crafting costs: 5 pistol rounds, and 3 magnesite ore.

Attachments
Pistol Sight - Increases zoom factor. Reward from the "Dangerous Territory" mission.

Pistol Suppressor - Suppresses pistol fire noise for stealth. Must be bought from the vendor for 25 Byzantine Coins.

Upgrades

 * (x) = Survivor Cost

Shadow of the Tomb Raider

 * AB .45: Nicknamed "The Altarboy" by Trinity Forces. A well-balanced pistol, good for all situations.
 * AB .45 - Gold Edition: Golden version of AB .45 obtained from the Social Rewards on tombraider.com
 * C&T S55: A semi-automatic pistol equipped with a high-capacity magazine.
 * J&D Model 27: What this pistol lacks in ammo-capacity it more than makes up for with its ability to deal heavy damage.
 * K&H KAP: Comfortable, reliable. A pistol to get you through the hard times.
 * River Hawk: A powerful pistol that deals high damage.

Trivia

 * 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 Darkness features Lara using them. She also carries two pistols no matter what.
 * When Roth has the Tactical Pistols, they have all upgrades (available to that pistol), but they are stripped away when Lara acquires them, until they are made by the player.
 * Adding the ergonomic grip to the Tactical Pistol will also add a "beaver tail" grip safety, which comes by default on the Semi Auto Pistol, despite that model of handgun not having one in reality)
 * Lara doesn't use Roth's pistols in Rise of the Tomb Raider, instead having a new pistol of the same model. However Roth's pistol's are featured in game in the Blood Ties DLC, where they are an obtainable relic.
 * The slide didn't lock back before Roth died, meaning that it is likely that the gun jammed, as opposed to running out of ammo, which would have resulted in the slide locking back.
 * Roth's pistols appear in the Blood Ties DLC as an artifact upon finishing it.
 * Interestingly, they are missing the muzzle brake.

Gallery
Dual Pistols