The Winchester 1866 is the loudest shotgun in the DayZ, and also the weakest. It makes up for this with its high magazine size, and the fact it's ammo is incredibly easy to find.
The Winchester is possibly one of the first weapons most new survivors will come across, due partially to the fact it's incredibly common, and also due to the fact it has a high spawn chance in any residential structures.
Despite its firepower (or lack thereof), the Winchester 1866 holds 15 rounds of 15Rnd. 1866 Slugs. This makes it excellent for raiding cities or small towns, as it can kill zombies with one shot regardless of where it hits due to its high initial damage.
Patch 1.5.8 removed the pellet ammunition type, and also lowered the 1866's raw damage, while also increasing the overall audibility by 25 meters.