The 127mm Compatto is a naval gun turret of Italian origin. It was developed in the late 1960's by OTO Melara at the request of the Italian navy. The Compatto design uses many technologies and principles found as found in the 76mm OTO Melara cannon. Recent upgrade plans include a longer 62-caliber barrel that may fire guided rounds at distances of over 100 km.

The 127mm Compatto naval gun turret was design for use on frigates and destroyers. It is usually mounted on the forward deck in front of the bridge. The unmanned turret has a single 127mm 54-caliber cannon that is connected to an automatic loading system and is flushed with either salt or fresh water for cooling. Most of the components are upscaled designs taken from the 76mm OTO turrets. The ammunition is stored below the deck and the gun is controlled by consoles installed in the ships command center. In the 1990’s a lightweight model has been developed.

The 127mm Compatto fires 127mm shells that are compatible with the US 127m L/54 shells. The rate of fire is selectable between 10 and 45 rounds per minute. The gun may be used to engage shore targets, naval vessels and aerial targets including helicopters, subsonic aircraft and incoming missiles. The maximum range is 23 km versus surface targets and 8.6 km versus aerial targets. Below deck there are three ammunition carousels holding 22 rounds each. Depending on the design 500 to 600 additional rounds are stored elsewhere in the ship.

For a large caliber turret the 127mm Compatto has been quite successful. Besides various Italian types of ships it has been installed on various South American and Japanese ships. One of the most modern classes to be fitted is the Dutch De Zeven Provincien class. The lighter and more modern Alleggerito turret model remains available for production.