Cannon

A Cannon is a type of heavy weapon that fires large-caliber shells. Cannons are most commonly found on Tanks, but can also be seen on other vehicles and as static emplacements.

Cannons use a mechanism that is very similar to that of any gun, including even handguns, but on a much larger scale. A typical modern Tank cannon has a diameter of 100-125mm, whereas earlier cannons can range from 75mm upwards.

Cannons fire armor-piercing shells that can destroy enemy armor; or HEAT shells that are less dangerous to tanks but much more dangerous to any other type of target. The shells travel at a low-angle trajectory (almost straight at the target), thus distinguishing cannons from Artillery which fires its shells in a high arc.

Cannons fire slowly due to the time it takes to load the next shell - whether manually or automatically. They have a very powerful recoil that is typically absorbed into the firing vehicle. The sound of a cannon firing can deafen nearby infantry, and this is even simulated to some degree in ArmA 3 as of 2018.

Non-tank vehicles carrying a cannon include the BMP-3 and Stryker MGS. SPG launchers, while technically similar to cannons, are not normally referred to as cannons in ShackTac. Smaller-caliber automatic cannons are called Autocannons, and have a much higher firing rate than any regular cannon.

Specifications
The term Cannon is a rather general term in real-life military use, and naturally even moreso in ShackTac. While all cannons share certain properties, their mechanism, use, and effect can vary wildly depending on many factors.

In principle, a Cannon is any projectile-firing weapon of a diameter larger than 20mm that is aimed and fired directly at its target. This definition includes such a wide variety of weapons - from hand-carried GP Launchers to gigantic naval artillery, and so is effectively useless for most purposes.

A more limited and more colloquial definition that fits the specifications of the ShackTac battlefield would be any such weapon of diameters between ~75mm and 125mm. The weapons within this category share many common characteristics, and make the term much more useable. Still, there are many differences to be pointed out.

The larger modern cannons (100-125 mm) are oftentimes seen on Tanks. They are very long and very powerful, propelling shells accurately over distances of several kilometers if necessary, while still maintaining (most of) their penetration properties. These cannons are rifled, which means that the inside of the barrel has a long groove bored into it that causes the shell to spin rapidly as it is being fired, giving it that flight stability. On the other hand it also means that the weapon can only fire very specific types of shells - those that have a specific matching rim to catch that groove.

The smallest (~75mm) modern cannons are typically found on smaller or older vehicles, such as WW2 tanks and modern IFVs. They are much shorter and less powerful than the modern tank cannons, but the shells still pack quite a punch. Nevertheless, the reduced shell size and velocity means that they do not puncture armor very effectively - especially the front armor of modern Main Battle Tanks - but can destroy other older tanks and IFVs reliably. ~75mm cannons are typically smooth-bore, meaning that the inside of the barrel does not feature any rifling. While this makes the shells less stabile during flight, it also allows some ~75mm cannons to fire non-shell projectiles such as ATGMs.

Cannon Shells
Cannons can and often do fire a variety of different shells that are suitable for different targets. The gunner manning this weapon can load a different shell type when the situation requires it, to better handle softer targets and conserve the "default" armor-piercing shells for harder ones.

Armor Piercing rounds are designed entirely to pierce the strong armor of heavy vehicles such as Tanks. Also called "Kinetic Rounds", "Sabot Rounds" and other similar terms, these shells contain a solid piece of metal that impacts with the target, punching through it and scattering metal pieces into the hull of the vehicle, destroying its machinery and killing the crew. These shells are fired at very high speeds and low angles, since they bank on their speed to be able to deliver as much kinetic energy into the target as possible on impact. These are the "default" shells for most cannons, and the gunners will typically switch back to Armor Piercing rounds after all softer targets have been dealt with.

HEAT shells rely on a different mechanism. These "High Explosive Anti-Tank" shells use a shaped charge that explodes on impact, compressing a soft material inside the shell into an incredibly hot jet that slices directly into the target's armor. HEAT shells are typically less powerful than Armor Piercing rounds, but are incredibly deadly against softer targets like IFVs and APCs. The explosion of the shell can also cause some collateral damage. Furthermore, HEAT shells do not rely on the speed of the projectile to maximize damage output, and can therefore are just as effective against distant targets. They are fired at a somewhat lower velocity and a steeper angle.

HE shells, for "High Explosive", are typically older shells used by WW2 tanks and modern field guns. These shells work by causing a huge explosion at the impact point, similar to most Artillery shells. While greatly lacking enough penetrative power to damage a modern tank, they are highly effective against lighter vehicles, groups of vehicles, groups of Infantry, and even against buildings. Tanks equipped with these shells are therefore extremely dangerous to infantry, light vehicles, and even APCs.

These are only general distinctions. In truth, there are many different shell types in each of these categories, and for each model of cannon. However these distinctions are largely irrelevant in the context of ShackTac videos, and most are not even modeled in ArmA to begin with.

Other Cannon-like Weapons and Terminology
In addition to the weapons described above, there are several other weapon categories that may overlap to some degree with Cannons, but are given different names in ShackTac to reflect specific important differences.
 * In the context of ShackTac / ArmA, Field Guns are cannons on a stationary mount, used for defending a static position. They can easily be placed behind plenty of protective cover, making them much more difficult to destroy than a vehicle-mounted cannon. Nevertheless, they are technically still cannons.
 * In modern warfare, small-caliber Cannons (20-40mm) are small enough to be fitted with an automatic self-loading mechanism that allows them to fire very rapidly. These are called Autocannons, and can be found on a variety of medium-class vehicles like APCs and IFVs, as well as many Attack Helicopters and Jets.
 * Recoilless Rifles, like the SPG, are ~75mm cannons that are light enough to be carried and operated by Infantry. They are most commonly seen in ShackTac mounted on Jeeps. Recoilless Rifles are typically deadly to infantry and vehicles, and enjoy the benefit of being a small target that's hard to spot.
 * Grenade Launchers are another modern invention that blurs the line, being essentially small, hand-carried cannons. They have a small-diameter barrel (20-40mm), and typically fire shells directly at the target. The firing mechanism of a Grenade Launcher, however, makes it somewhat more akin to an Artillery piece, and they are usually classified as such.