Rail Rifle - History: Even before the Tau Empire's First Sphere Expansion had drawn to a close, Earth Caste scientists turned their efforts to further refining Rail Weapon technology, the goal being to create a version compact and durable enough for use by a Fire Caste infantryman. Thus did the development of the Rail Rifle begin. Success was not immediately forthcoming. Early Rail Weapons required substantial shielding in order to avoid flooding their Hammerheads and Battlesuits with harmful levels of radiation. These shields were inevitably formed of super-dense metal alloys, and contributed greatly to the mass of the weapon. Even when the payload of the prototype Rail Rifle was reduced, allowing a comparable reduction in power requirements, the weapon was too heavy to be carried by fewer than three Fire Warriors, and was therefore relegated to seldom-used defensive emplacements.Progress was slow for many standard years. The Earth Caste reduced the Rail Rifle’s bulk by increments, but never by enough to meet their stated objective. Nevertheless, their labours were not wasted, as many of these refinements were retro-fitted onto existing Hammerhead and Broadside Railguns. Even though the goal of a Shas’la-portable Rail Rifle was still some way off, Rail Weapon technology as a whole was becoming more compact, more accurate and cheaper to produce with every year that passed.The breakthrough finally came in the Second Sphere Expansion, during the campaign known to the Imperium as the Damocles Gulf Crusade. Here, the Tau were faced with a better-equipped enemy than any they had fought before, and the resulting conflict spurred unprecedented advancement in all fields of Tau scientific endeavour. Amongst the developments was a new ceramic, named or’es’var – literally "mighty bulwark" in the Tau Lexicon. Originally conceived as an ablative hull material to counteract the devastating effects of the Imperium’s fleet-borne Nova Cannons, the material was soon discovered to have unparalleled radiation absorption across a wide spectrum -- and better than that, it was light, almost weightless. With the way forward finally revealed, the Earth Caste presented the Fire Caste with the first prototype Rail Rifles.At this stage, the Rail Rifle was still undergoing field trials with specialist units, but it was hoped that the new weapon could be issued more widely and eventually mass-produced. The relatively slow rate of fire, the bulk of the weapon and the early, unstable targeting mechanism did not meet the expectations of the Ethereal and Fire Castes, and these early prototypes often displayed a dangerous malfunction where the immense power generated by the weapon could generate fatal feedback through the Rail Rifle's neural targeting system. Yet the Rail Rifle's ability to penetrate armour made it highly valuable to Tau forces despite the difficulties incurred in its development. Indeed, it was found in early testing against various armour types in the Tau arsenal that only the armour used in XV88 Broadside Battlesuits could offer any protection against its fire. The weapon was capable of penetrating even the hardened carapaces of the larger Tyranid bioforms. The impact of the Rail Rifle was also such that its target was frequently hurled bodily by the impact, and this effect, combined with the distinctive whine of its hypersonic slug, often had a demoralising impact upon the foe.Further developments of the weapon and refinements in its design eventually removed the risk of dangerous neural feedback to the user, and the weapon was issued to frontline Pathfinder units for field testing. This stable variant of the Rail Rifle has since been improved upon throughout the Third Sphere Expansion until it has reached its current refined state. At the sacrifice of a small modicum of range, the Rail Rifle is now used on the move more easily and can be fired faster. Its projectile can penetrate all known forms of infantry armour and even poses a threat to lightly armoured vehicles.Now, centuries after its first development, the Rail Rifle is a common sight in Pathfinder vanguard and reconnaissance teams, though it has not yet fully supplanted the Pulse Carbine. Indeed, current Fire Caste doctrine dictates that Rail Rifles never be fielded to the exclusion of all other weaponry. Even though the current models are considerably more reliable than the initial prototypes, they are still prone to occasional misfires or targeting system failures. These mishaps occur rarely-- perhaps once in ten thousand firings -- but until this minor quirk is rectified, the Fire Caste will consider the Rail Rifle an augmentation to Pathfinder Teams, rather than a mainstay weapon.Whilst Rail Rifles officially remains exclusive to Pathfinder Teams, there are persistent rumours that more compact versions of the weapon are currently being trialled by Fire Warrior cadres on the Tau Empire’s eastern fringe. It is difficult to say whether there is any truth to these tales, though it is certainly the Earth Caste’s avowed intent to oversee further refinement to the weapon. Their next goal is to evolve the Rail Rifle to a point where its killing power is comparable with its larger, Broadside-mounted cousins.