The MB-2 rifle was a large, heavy, yet rugged and reliable selective-fire rifle that sported two barrels, each with their own xCiter chamber, which could fire together, or in an alternating pattern. The rifle's output and characteristics could be adjusted using controls located on the left of the receiver, just behind the gas magazine well. The rifle featured an advanced holographic imaging scope on either side of the receiver which could be wirelessly linked to a HUD, and it was notable in that it also had iron sights that could be used in the event the imagers failed. The rifle had a large blaster pack to accommodate high power consumption, and a large gas magazine that could be inserted from the left or right side depending on the firer's preference. Finally, the rifle could interchange a collapsable or fixed stock, and featured a low-ammo indicator on the grip, which vibrated when the number of remaining shots went below fifty.
Originally designed by Sprig Arms, a Velmoran firearms company, the MB-2 became standard issue for Velmoran defense forces just before the RLF/Imperial war. It gained noteriety as a powerful and fearsome weapon, especially distinctive with its two barrels which enabled a relatively high rate of fire despite its high yield.
Sprig Arms sold three variants of the MB-2 to authorized dealers and military organizations. The latest incarnation of the standard rifle was the MB-2A1, while a shortened carbine variant, the MB-2K, was also sold. Often, a conversion kit was sold with the original MB-2A1 so that it could be manually reconfigured into the MB-2K. The final variant was a designated marksman, or sniper configuration, which featured an elongated barrel and fixed stock. This variant combined the xCiters' power output to create a beam from only one barrel of the two, which decreased the firing rate and heat radiation while greatly improving output and range.
After the formation of the PGA, the PGAF began to standardize its forces, organizing the disparate and motley assortment of volunteer freedom fighters who formed the RLF into a disciplined and uniform military. Given the strong influence of Velmor on the RLF, it was not long before the MB-2 was selected as that standard firearm. The rifle was redesignated the Model 1 (M1) Sprig, and issued to most PGAF Marine enlistees and many AIR commandos, while the MB-2K was introduced as the M1 Spring Carbine and issued to NCOs and officers. The range of the rifle was deemed suitable enough to be used by snipers, but the PGA did issue the MB-2S in limited operation, although this was not widespread.