Small, lightweight, and compact. A Calico .75, which was produced by Romano & Bianchi Weapon Systems, one of the Alliance's largest weapon contractors the Calico weighed only nine and a half pounds and was twenty eight inches long, much different than traditional larger and heavier sniper rifle systems employed by most armies over the course of history.
The Calico relied on accelerating it's mineral composite rounds at near light speed. However firing a round of it's caiber, the Calico could only fire twice before overheating to a point where if it was fired again it could quite literally explode.
Upon it's second shot fired, the heat energy produced from mass accelerating it's rounds would collect in a thermal clip which needed to be ejected by cycling the rifle's bolt and moving the next thermal clip into a position to collect heat buildup from the next shots to be fired. Up to six thermal clips could be loaded into the rifle at a time before more were required to be loaded into the rifle via an injection slot located on the side opposite to the bolt and ejection slot on the right side of the rifle.
The munitions fired by the Calico were incredibly powerful and made of a mineral composite alloy which consisted of 27% steel, 22% nickel, 13% copper, 29% titanium, and a hardened 9% white phosphorus compound which was designed to break upon contact with a target after the armor-piercing mineral composite pierced any armor to maximize its useage and performance as an incendiary round.
Though expensive to produce like the rest of the Calico Sniper Rifle System, the mass accelerated slugs fired by the Calico were among the most powerful in the Systems Alliance Military. Though technically in violation of the Thessia Convention of 2162 CE which the Systems Alliance ratified along with the Asari Republics, Turian Heirarchy, Batarian Hegemony, and the Salarian Union. The Calico's unique munitions were deemed to be "cruel" and a "needless infliction of pain" on their victims by the Asari Republics in 2178 CE.
The Alliance responded to the asari claims by offering to donate eighteen billion credits to medical charites designed to aid civilian and military victims of war-crimes. This was a major setback in Alliance defense funds and was met with cost-cutting measures which limited the Alliance's purchase of Calico Sniper Rifles and other Romano & Bianchi weaponry.
By 2181 CE the Alliance stopped purchasing the Calico Sniper Rifles from Romano & Bianchi and due to their exclusive owner-ship of rights to own all Romano & Bianchi weaponry purchased in 2145 CE for fifty-eight billion credits. Production stopped altogether after the Alliance stopped purchasing it and it was retired officialy from service on New Years Day 2187 CE.