Cannons are essential tools in the modern battlefield. They provide the ability to attack areas from greater range than infantry, and bombard enemy defenses to prepare for an attack. Cannons can be found on almost every military vehicle, and is the standard method to engage other vehicles. There are 5 different cannons currently in the game, each fulfilling a unique role.
Cannons have several modes of operation, which are listed here. Note: Do not press the stone buttons on the cannons, or the cannon will be destroyed. This is a known bug.
When a cannon is first created, it needs to be scoured. In order to scour a cannon, right click it with a stick in hand. Firing projectiles will also cause soot to build up, which requires scouring to remove. The amount of scouring required depends on the gunpowder used. Note: Machine Guns do not require scouring.
When a cannon is fully scoured, right click on the cannon block with gunpowder in hand to prime the cannon. Different cannons require different amounts of gunpowder. Careful, as loading too much gunpowder will cause the shot velocity to increase, but there is a chance the cannon can explode. After priming the cannon, right click the cannon block with the projectile ammo in hand you wish to load. The projectile then needs to be rammed with a stick. Right click with a stick to ram the shot. The shot is now ready to be fired!
Manual Aiming and Firing
In order to aim the cannon, you have to right click on the cannon block with an empty hand. Right clicking on the left will aim the cannon left one tick, right clicking on the right will aim the cannon right one tick, and right clicking on the top will aim the cannon up one tick. In order to invert your action, hold shift while right clicking. E.g. shift-right clicking on the top will aim the cannon down one tick.
In order to fire the cannon, right click on the lever. Stand back from the front, as being too close to the muzzle will cause damage and nausea.
If a chest is next to a cannon on one of the designated spots, and loaded with gunpowder and projectiles, it can autoload. Simply shift-right click on the lever in order to autoload a projectile. During auto-loading, there is a delay where the projectile cannot be fired, which depends on the cannon type.
While holding a clock in hand, right click on the cannon block; you will enter auto-aim mode. Auto-aim mode does not require the clock to be constantly present in your hand to operate. To aim the cannon, hold shift and look around. The cannon's aim will match the current direction of the player. The cannon will not account for parallax, so the block you are looking at will not be the block the cannon is looking at. If you are looking towards 20 degrees, the cannon will be aimed towards 20 degrees.
If the cannon is unloaded and able to be autoloaded, you can autoload it by pressing shift-right click. This will autoload a shell.
In order to fire the cannon when it is loaded, right click.
In order to exit autoaim mode, right click the cannon with a clock, or walk far enough away from the cannon.
Cannons can be fired using redstone contraptions by placing a redstone torch underneath the cannon. When the redstone torch is turned on, the cannon will try one of two things. If the cannon is unloaded, it will try to autoload from an attached chest. If the cannon is loaded, it will try to fire the cannon.
Rotation using Movecraft
If a sign is placed on a cannon with "Subcraft Rotate" on the first line, and "Cannon" on the second line, a cannon can be rotated 90 degrees using movecraft. Left click the sign to rotate left, and right click the sign to rotate right. In order to remove Subcraft Rotate signs, either world edit has to be used, or the block he sign is touching must be destroyed. The sign will rotate touching iron blocks, iron bars, stone buttons, levers, glass, signs, lapis, chests, iron pressure plates, and obsidian. The system is similar to turrets, but the block list is much more limited.
Certain cannons (Mortars and Long Cannons) can use the impact indicator. This is a a bunch of glowstone in a bundle that moves when you aim the cannon while the cannon is loaded with a shot. This is approximate, as the cannons have a certain inaccuracy involved. This impact indicator only will work to the render distance from the cannon, and will not show up past that. An empty cannon will not display an impact indicator.
A second player can view your impact indicator using the command "/cannons observer" and then right clicking on the cannon. The player will then see the impact indicator when you aim. Note: viewing multiple cannon impact indicators does not work properly, and will cause flickering. Using the same command again and right clicking on the same cannon will remove you as an observer.
Important: The glowstone the indicator creates is not real and is only visible on your client. Jumping on the glowstone will result in you being kicked for flying.
By placing a sign on the side of the cannon, you can display information about the cannon. The cannon will display following information on the sign: The name of the cannon, the owner of the cannon, the amount of gunpowder loaded (p), the temperature of the cannon (c), and the current angles of the cannon (h/v).
There are 5 different cannon types currently in the game. Not every cannon will fulfil every role, and not every cannon type can fit on every vehicle. For example, the AA Tower can only be placed on three vehicles, so other vehicles will need to be escorted to fight off airships.
The regular cannon is the general purpose cannon. It can use almost every type of projectile, and does not require obsidian. The range is limited to roughly 130-140 blocks without overloading, which is just about the edge of the render distance. The quick autoloading time of the cannon means that it can out-fire a long cannon using autoloading, while using less gunpowder. The lack of obsidian means that it can fit on most military vehicles without a problem.
The long cannon provides the role of long range artillery. It can fire every round the regular cannon can, but faster and further. The high velocity will also mean there is practically no drop for short range, and it will increase the penetration of round such as the AP shot. While an AP shot with a regular cannon pierces only 1 block of cobblestone, the long cannon can pierce at least 5 cobblestone blocks with an AP round at close range before the round detonates. The long autoloading time means the cannon is best used while manually loading.
For ranges beyond render distance, its best to use manual aiming and another player for spotting. The impact indicator will not work beyond the render distance from the long cannon, so the shots must be manually ranged in using the other player. Note that the cannon is not accurate at its maximum range so expect a spread of shots when firing salvos.
Mortars are similar to regular cannons in the range, but they fire indirectly, traveling upward instead of forward. This means the time to target is longer than a regular cannon, making hitting moving targets difficult. The benefit the mortar provides is against units behind walls, whether your own or the enemies. While a regular cannon would have to destroy the wall first, the mortar allows the projectile to land from the top onto the target. The other downside to the mortar is the lack of obsidian-breaking shells, and a slightly lower range than the regular cannon. The mortar is best used with another player as an observer who can spot the impact indicator.
The mortar doubles as a simple anti-aircraft gun for engaging low flying airships. Since most ships cannot carry an AA tower, a mortar is their best defense for an overheard aircraft.
The machine gun is the ideal weapon against groups of enemy infantry. Each iron ingot will produce 50 rapid firing projectiles that can quickly kill even armored players. The machine gun cannot damage blocks, allowing it to defend areas without risking damage. The autoloading time is almost instantaneous, making autoloading almost a necessity. Using autoaim, you can continue aiming the cannon as the shots are fired, allowing effective suppression. Since the weapon cannot damage blocks, machine guns are practically useless against enclosed vehicles. Ensure your machine gun has a long enough firing lane, or else infantry will quickly be able to outflank your machine gun positions.
The AA (Anti-aircraft) Tower is a magnificent sight to behold. With its standard 20 round Rapid AA Magazine, it can shred through any airship in a matter of moments. No other projectile type is needed, as they are relics from a forgotten age. The AA tower will strike fear into the hearts of all airship pilots. To limit the AA tower's use to exclusively airships, the minimum depression of the cannon is +25 degrees. This means airships traveling along the ground will be immune, but they will be vulnerable to all the other cannons.
Note: While the aircraft gun can traverse in a complete circle, doing so will wind the tower completely. If this happens, you will need to traverse the gun all the way around the other direction in order to continue.
There are 6 standard projectiles that most cannons use, and 3 projectiles the AA tower can use, and 1 projectile the machine gun uses.
The Ball shot is actually a magazine of 5 weak rounds. The ball has no penetration, and only has enough explosive power to damage wood planks and below. Terracotta will be completely immune to ball shots. This makes the projectile useful against infantry and lightly armored targets such as most airships. The accuracy and range of the ball shot is less than most, so expect a spread of shots when using ball.
AP rounds have different effects based on its velocity. When shot out of a regular cannon or mortar, it will break a single block on impact before detonating with the power of tnt. When fired out of a long cannon, the projectile will travel through several blocks, breaking them in the process, before exploding. This latter ability makes the AP round capable of destroying cobblestone bunkers with ease. Without a high velocity, the round is simply a cheaper version of an HE round.
This expensive round is considered by some to be the real general purpose round, but the materials to make the rounds are generally rare. The damage output of this shot against the surface of any object is tremendous. This round can be used against anything that isn't made of obsidian to break the other shell. The only time this shell fails is when penetration is required, or obsidian is encountered.
When encountering pirates and airships only made of wood and wool, the incendiary round is quite useful. While less powerful than the AP round, the area it hits will be set ablaze. Fire will quickly spread across wood and wool, and will also block vehicles that try to move through it, potentially disabling it. However, be wary of the pirates' waterbottle ability!
Whenever obsidian is encountered, an APKEP round is useful to have on hand. When the round hits a target, it will continue travelling for 10 or more blocks into the target, destroying many blocks in a straight line. This is useful when trying to make holes in obsidian armor so more explosive round can be used on the inside, or when trying to hit vital components behind thick armor.
The APHE round is a sight to behold. The round will burrow through obsidian armor, and cause a large explosion on the inside. It also will spawn a cluster of 4 new projectiles that will also penetrate obsidian and explode. Do not be anywhere near the target when one of these hits, or else you could be hit by one of the subprojectiles.
Machine Gun Magazine
The machine gun magazine is the only ammunition available to the machine gun, but it serves its purpose well. With 50 shots per iron ingot, the machine gun can sustain fire on the enemy with little resources expended. Each shot will seriously cripple a person, but will do no damage to blocks.
Rapid AA Magazine
The AA Tower's only required magazine, with a massive clip size of 20 round capable of destroying wool, wood, and terracotta. The Rapid AA Magazine will make short work of any airship that takes a full brunt. These round will only travel for 5 seconds before exploding, preventing their use against land targets.
Rapid AP AA Magazine
A relic of a forgotten era when monstrous obsidian war machines cruised through the sky. There is rarely a need to ever use this magazine.
For the times when setting an airship on fire is required, the AA HEI shot comes in handy. While the Rapid AA Magazine will do much more damage, the fire has the potential to strand the airship in the air without the ability to move. Only one shot per iron block, so usage is limited.