In GTA III Era games, the shotgun takes the form of a Franchi SPAS-12. The weapon's gas-powered repeater system holds seven shells in the magazine tube. It is fully automatic in the GTA Vice City rendition, however this feature was removed in later installments, presumably to balance the weapon. It is not commonly found throughout the games it appears in; in GTA Vice City, only one Ammu-Nation store sells the gun, at the extremely high price of $4000, with a similar situation in GTA San Andreas. In GTA Liberty City Stories, the gun can only be obtained through one set spawn location.
This weapon is spelled as "Spaz 12" in the original PS2 version of GTA Vice City and in GTA Vice City Stories; and as "S.P.A.S. 12" in later versions of GTA Vice City.
In Grand Theft Auto IV, the Combat Shotgun takes the form of a Remington 11-87 semi-automatic shotgun, with a thumbhole stock, 24-inch barrel with a fully ventilated rib, and a full-length magazine tube with sling swivels. The Combat Shotgun holds 10 shells in the magazine, and 70 in reserve. When the player enters any LCPD or NOOSE vehicle, the player is given this shotgun with five shells, if the slot is not already occupied. In the The Lost and Damned, the Combat Shotgun has been changed to have a pistol grip and tactical stock, similar to that of the M4 (although the Combat Shotgun retains its earlier form in Terry Thorpe's gun van). This design is not carried on to The Ballad of Gay Tony, which instead features the original design.
Ocean Beach - North of the helipad by Lance Vance's home next to a house surrounded by bushes on all sides.
Grand Theft Auto IV
The Combat Shotgun can be purchased at the back-alley gun shops for $2500, and each additional magazine is $200. The player can also purchase one from Little Jacob for $1500, with each additional magazine costing $100.
Schottler - Can be found on the ground floor of an apartment building on Cassidy Street, leaning against the wall behind a staircase. It will more than likely be encountered during the mission Blow Your Cover.
Castle Gardens - Can be found in a vacant room in the Castle Gardens construction site. This gun may be useful in the mission Deconstruction for Beginners. The room is difficult to find: it is to the northeast of where the helicopter lands during the mission, down a ladder. The last contractor is usually killed on the ladder opposite.
In GTA IV, TLaD, and TBoGT, blind-firing the shotgun from behind cover results in the character pumping the shotgun after each shot, as if he was using a pump shotgun. It is unknown whether this is a glitch or done for balancing purposes. This also happens with the Sawed-off Shotgun, although this stretches far from reality.
The actual SPAS 12 shotgun is seen in GTA IV's loading sequences; artwork shows two NOOSE officers, one holding a SPAS 12, and the other holding an MP10.
Despite the fact that the player gets the combat shotgun when entering an LCPD or NOOSE vehicle, the LCPD and NOOSE officers use Pump Shotguns.
In GTA Vice City, GTA Vice City Stories, GTA San Andreas and GTA IV, the combat shotgun has an unrealistic reload animation, where in the player pumps it during the animation. The player should instead pull the charging handle located on the right side, as the SPAS-12's pumping handle is locked when it is being used semi-automatically. GTA IV's combat shotgun should also have a charging handle on the right side by default; the real one on which this shotgun is based does not have a pumping handle.
In real life, the SPAS 12 is illegal to import (but not to own), so it is likely that Ammu-Nation sells it illegally, alongside the also illegal Sawn-Off Shotgun.
The real life SPAS-12 is capable of both pump-action and semi-automatic fire modes, but in-game, it only utilizes the semi-automatic fire mode.