obrez
An obrez is a rifle that has been hastily converted into a makeshift handgun by shortening the barrel and sawing off the shoulder stock. The canonical obrez is based on the bolt action Mosin-Nagant. The term is a Russian word that means "sawn-off" or "cut-off".
It supposedly originated during the Russian Revolution of 1917, when revolutionaries are said to have captured/stolen military rifles and cut them down for concealability purposes. In practice, a full-power military rifle circa the turn of the 20th century makes for a ludicrously unwieldy handgun, and although contemporary examples do exist in museums today, there is little evidence that they were ever employed in large numbers.