MP5SD6
The MP5SD6 is a silenced submachine gun, and is one of the quietest weapons in DayZ. Its noise is barely audible, even by the player while shooting. Because of the low noise and relatively common magazines compared to the other silenced guns, this weapon is one of the best choices for stealth close quarters actions. The main downsides of this gun are its lack of damage, the not so good iron sight, which can be difficult to use for some players, and the low accuracy at long ranges.
The MP5SD6 can also use M9SD Mag., which is carried in the sidearm ammunition slots, freeing up space in the main inventory. The unsilenced version can can also use the other 9x19mm pistol clips.
It spawns in most military buildings, with the notable exception of the northwest airfield barracks. Its spawn chance is half of its unsilenced variant, the MP5A5. Ammunition has a chance to spawn in most loot locations, with the highest chance being in military spawns.
Also, once you get used to the sights, this firearm is perfect for taking out zombies out to 100 meters (the sights combined with the subsonic 9x19mm makes for a rather rainbow trajectory). It can also be used to engage players in a pinch at close range, either by semi-auto center-mass shots, or use the burst setting to put a 3 round group that'll drop them very quickly. The only sound you're able to hear within 10 meters is the bolt cycling.