A barrel bolt lock, also called a sliding bolt lock or a shoot bolt, is a simple locking system used to secure a door from a single side. The barrel bolt lock has two main components: a sliding metal bar and a catch plate. The catch plate is mounted on the door frame in such a way that the sliding metal bar or bolt can easily fit inside the opening of the catch, thus physically blocking the door from being opened until the bolt is retracted.
Although the majority of barrel bolt locks have a round bolt, some models incorporate a flat sliding bar. In all cases, the bolt will have some kind of knob attached or built into the design of the bolt, allowing the user to grab the knob and slide the bolt into the hasp. In some cases, the bolt might rotate at the end of its slide to place the knob in a locked position or have some other security measure in place to avoid having the lock compromised.
Barrel bolts are available in many metal types to suit the needs of specific projects. A lightweight brass barrel bolt might be a stylish yet moderately functional locking system for a kitchen cabinet or curio case. For situations requiring a sturdier, more functional barrel bolt lock, such as securing the front door of the home or the gate of an animal enclosure, a stainless steel barrel bolt might be the more appropriate choice.
In addition to the various metals used to create barrel bolt locks, barrel bolts also come in a variety of sizes. Some barrel bolt locking mechanisms are smaller and serve more of a cosmetic purpose than an actual functional purpose. These barrel bolts can have a total bolt length of less than 2 inches (about 5 cm), and the bolt might be 0.25 inches (about 6 mm) or less in diameter.
Larger barrel bolts, including a tower lock, are used when security is required. An example of this application is the use of a barrel bolt lock to secure the front entry door of a home. With bolts as long as 8 inches (about 20 cm) and bolt diameters of 0.75 inches (about 18 mm) or more, these barrel bolts provide a strong yet low-cost security solution for applications in which a keyed locking system is not required or desirable.