Door breaching
Door breaching is a process used by military, police, or emergency services to force open closed or locked doors. A wide range of methods are available, one or more of which may be used in any given situation. Regarding the use of specified tools for forcible entry, there are several other methods of door breaching. These methods may be divided up into mechanical breaching, ballistic breaching, hydraulic breaching, explosive breaching, and thermal breaching. Common methods. Where no tools are available, it is usually possible to force open most inward-opening doors with a strong kick that breaks through  the door frame. This can be a common method of entry for many trained police officers who are conducting searches, most interior doors can be forced by kicking. Converse to most movies, the safest method to kick a door is back kicking, with your back to the door. This method reduces the chance of injury to the breacher. Kicking in a locked door is also sometimes attempted or performed by neighbors and ordinary passers-by who witness an emergency situation such as a house that is on fire (though the first step should always be to call emergency services) in  order to ensure that everyone is out of the house or to notify/assist anyone who is not. Kicking in doors is less commonly used in burglary attempts since the process requires a great deal of energy and makes a lot of noise. Types. Mechanical. Mechanical breaching can be minimally destructive, through the use of lock picks. This method is relatively slow and requires a trained operator, but does not damage the lock or door. Using specialized tools (i.e.: A-tool, K-tool), a lock cylinder can also be quickly dismantled and unlocked without removing it from the door; this  method also allows the door to be closed and re-locked. Mechanical breaching also includes hydraulic breaching, which uses a special hydraulic ram to overcome the lock. The hydraulic ram may be powered manually, pneumatically, or electrically. More dynamic methods (kinetic breaching) use force to break the lock or door. The common methods are to use a lever, such as a Halligan bar or crowbar, or to use a tool to concentrate a large amount of force on the door, such as a sledgehammer, hydraulic jack, or battering ram. Ballistic. Ballistic breaching uses a projectile weapon to breach an opening . Weapons used can range from small arms to the 120 mm cannon of a main battle tank with a high-explosive anti-tank (HEAT) round, which will breach most obstacles easily, though the force involved may violate the rules of engagement. A less damaging ballistic breach needs to destroy either the latch and lock, or the hinges of the door, and the ideal choice for this is the shotgun. While in theory other firearms can be used, handguns are usually underpowered and rifles are less effective than the shotgun and pose a far higher risk of ricochet and collateral injury . Most shotgun ammunition can be used for breaching, though the risk of injury varies with type. Of the available shotgun ammunition, shotgun slugs pose the highest risk, as they will retain significant energy to cause lethal wounds well after they have penetrated the door. Buckshot is far safer and birdshot even more so, as the multiple small projectiles disperse quickly after penetration, reducing the chances of causing a lethal wound. The safest option is a frangible round such as the TESAR or Hatton round, which turns to dust upon penetrating the door, and disperses completely upon exit. Breaching a door  with the fewest shots possible both is faster and reduces the chance of collateral damage. Attacking the latch and lock is easiest, as it requires fewer shots and is easiest to target, whereas attacking the hinges requires more shots, and the hinges may be hidden from the outside. Careful aim is required; shots to the lock side are fired at a point halfway between the lock or handle and the door frame in order to hit the bolt holding the door shut. According to US urban warfare doctrine, the breaching operation is performed with the muzzle in contact with the  door, or as close as possible, and angled downwards at a 45 degree angle. This process provides the best chance of hitting the desired point, while minimizing risk to occupants of the room being breached. Muzzle attachments are available on some specialized breaching shotguns to facilitate this operation, by holding the barrel securely in place while providing a slight standoff to allow powder gases to escape. Magazine capacity and operating mechanism are also important considerations in a breaching shotgun, because to quickly breach a door requires the ability to quickly fire multiple shots. For a breach on the latch side , US doctrine calls for two shots to be fired, and then an attempt made to open the door. If the door cannot be opened, the process would need to be quickly repeated. If the hinges must be breached, then doctrine calls for a total of three shots, one per hinge followed by an attempt to open the door. Explosive. Explosive breaching can be the fastest method, though it is also the most dangerous, to both the breachers and the room occupants. Depending on the situation, explosive breaching is potentially slower than a ballistic breach due to the large standoff  required when using explosives, if there is no cover available. Breaching can be performed with a specially formed breaching charge placed in contact with the door, or with various standoff breaching devices, such as specialized rifle grenades like the SIMON breach grenade. Breaching using explosives is primarily an operation performed by highly trained explosives experts. Explosive breaching charges can range from highly focused methods, such as detcord, plastic explosives, or strip shaped charges that explosively cut through doors or latches, to large satchel charges, containing 20 pounds (9 kg) of C-4, that can breach even reinforced concrete bunkers. Explosive method  of entry can be a safe and effective tool in the hands of qualified breachers. It is the mission of the explosive breacher to use the least amount of explosive needed to secure penetration to a target. This can often be accomplished using less than a quarter of a pound of explosives when used correctly. In addition to the tactical use, explosives have been used for search and rescue or other critical access situations. Thermal. Thermal breaching is one of the least common techniques and also one of the slowest. It involves the use of a cutting torch to cut  through metal doors.