The No.5 MkI Enfield, commonly called the “jungle carbine” is nearly the shortest-lived rifle in British military service (second to the Rifle No.9, aka EM-2). Introduced in 1944, they were declared obsolete in 1947 as the result of insoluble accuracy problems. The guns were originally developed from regular No4 Enfield rifles with the goal of producing a shorter and lighter variant for paratroops. This was done by shortening the barrel, adding a flash hider, and making lightening cuts in several places on the barrel and receiver (which were the cause of the problems that doomed the gun).
Not all No.5 rifles produced developed problems, and they were certainly handier than the regular Enfield rifles. They are noted for kicking harder, of course, and this is not really helped by the narrow rubber buttpad they came with (most of which are nice and hard today).