Autocannon

Overview
The bread and butter of most Dominion combat systems, big or small. Autocannons are defined as: any gun that fires projectiles wider than 20mm in diameter with a fully-automatic firing mode and maximum sustained fire rate in excess of 60 RPM. As most modern ballistic and electromagnetic systems are capable of meeting all three of these criteria; most kinetic guns used by the Dominion are technically autocannons- hence the popularity of the term.

Mechanism
The mechanism of autocannons varies depending on the scale and desired characteristics.

The most widely used mechanism is condensed thermonuclear propellant which is particularly common among spacecraft turret units due to their massive bores and firing chambers, capable of fitting large amounts and resisting immense chamber pressures. These typically use a highly efficient pure fusion-based mixture.

A more powerful but dangerous alternative is antimatter propellant. This is not preferred unless the additional power or space efficiency is required due to the associated storage issues, damaging chamber pressures, and somewhat higher complexity of transmuting matter with a reversed charge. However, this propellant is undeniably far more energy-efficient than even the best fusion-based mechanisms. Typical safety mitigations utilized with antimatter based autocannons are a neutrite (NOT to be confused with degenerate neutronium) coated chamber that uses a pure antiproton based mixture to avoid reduce the chance of unintentional annihilation and no buffering of propellant- requiring a full transmutation between shots, which usually considerably slows the fire rate.

A rarer mechanism is that of a simple coilgun, optimized, and upscaled to perfection. Unlike the other designs, this does not rely on transmutation between firing cycles and is more energy-efficient. However, the mechanism itself is incredibly elaborate, complex to produce, prone to numerous minor failures, fragile, and most damning of all: less space-efficient as it not only requires a wider and lengthier barrel to achieve competitive velocities but also a bulky power bank in the place of a traditional pressure chamber. Despite all this- the coilgun mechanism does see limited use on larger platforms, where the increased energy efficiency can make a significant difference in the sustained rate of fire, overall projectile velocity, or both.

Usage
Autocannons see universal use across all theatres of combat in the Dominion. This is due to their: simplicity, efficiency, reliability, support for numerous different ammo types, and the overall effectiveness of kinetics, both relativistic and super-relativistic. Infantry variants range from low footprint coilguns to massive cannons. Spacecraft variants encompass a broad range of shapes and sizes from rapid-fire point defense emplacements to colossal star vaporizing turrets and multiple parsec long spinal mounts.