Adam-ska Special

The Adam-ska Special is a specially customized AM D114 pistol with black frame and ivory grip, with engravings all over it. It's statistically similar to the level 2 AM D114 pistol, excluding the ability of using a silencer. It's

A bonus item included with the Day One edition of Metal Gear Solid 5 and maybe even the collectors edition.

It can be seen in a cut-scene where Diamond Dog trainees are shooting at targets with AM D114's with Ocelot instructing them. One soldier is firing the Adam-ska special from his hip, in which Ocelot tells the soldier that the weapon is an automatic so there is no need to compensate for the recoil, the engravings have no tactical advantage in the battlefield, and that the soldier is better suited using revolvers.
 * This is a reference to Metal Gear Solid 3, in which Big Boss (then called Naked Snake) tells the young Ocelot that he isn't cut out for an automatic during their first encounter in the Virtuous Mission, then during Operation Snake Eater Ocelot returns with an engraved Single Action Army, to which Big Boss tells him that the engravings give no advantage.