Faced with the reality of modern warfare after the debacles of the second World War, Tahar Joblis commissioned a new standard infantry arm. Discarding the musket was well overdue.
Thus was born the new Rifled Musket. Initial testing proved rather disastrous in spite of foreign aid in development; the Rifled Musket was awkward, difficult to handle, and tended to explode when used. This naturally led to an official Tahar Joblissan Army project looking into the matter as opposed to foreign contractors attempting to fulfill the outdated requirements of said body.
The Tahar Joblissan Army having one of the largest bodies of fully qualified materials engineers on the face of the planet, it took relatively little time for the Rifled Musket With Some Design Work Re-Done On It, abbreviated RMWSDWRDOI for convenience's sake, to begin mass production in the hands of the Army and the old musket gunsmiths the Army had just extensively retrained. When the combat elements of the Army finally began training with the finished product, they pronounced it "amazing," vastly outperforming the muskets of yore in power, accuracy, and ease of use. They also pronounced it "unpronouncable," and immediately shortened RMWSDWRDOI to "Rumsudoi."
The Rumsudoi would remain the standard infantry weapon of the Tahar Joblissan Army for more than half a century until the development of the TJSC-25AP sniper rifle (and associated TJSC-25C carbine rifle) and the TJAR-MX/MG assault rifle, and remains in use as a readily available anti-material weapon. The Tahar Joblissan Marines never officially adopted the Rumsudoi, prefering smaller weapons with higher practical rates of fire.
The standard model Rumsudoi measures 7'3" in length, 8'11" with standard bayonet attached. The Rumsudoi fires a .64 caliber bullet with a length of 117mm, an unpredented slug size for a "standard infantry weapon," at a high velocity. It has a kick like a mule in spite of being very well engineered, and is a single shot breech loaded weapon. It has been occasionally exported as a squad anti-material weapon or a vehicle-mountable weapon.
The First Rifle Company of the Tahar Joblissan Army drill constantly with their Rumsudois and swear by them. They make quite a sight when they do their pike formation drills in parades, sometimes wearing unpowered "light" armor suits.