Ferdinand von Mannlicher was a brilliant and prolific European gun designer with more than a few widely-adopted military arms to his name. One of his very last guns was this carbine, which was also one of the first intermediate cartridge carbines developed. It was a mostly experimental gun, and never saw large-scale production.
Mechanically, the gun is an evolution of his 1896/1901 automatic pistol and the 1901 carbine made from that pistol. It locks using a short recoil action and a tipping bolt, and was initially made in 7.63mm Mannlicher (dimensionally identical to 7.63mm Mauser but slightly less powerful). One of the shortcomings of the 1901 carbine was that the handguard was fixed to the recoiling barrel, so that a firm grip on the handguard would cause the gun to malfunction. The 1901/04 variant of the carbine fixed that issue by connecting the front handguard to the trigger frame, which did not move during cycling.
The most significant change of the 1901/04 design, however, was its size being scaled up to use a larger 7.63x32mm cartridge (sometimes misidentified as 7.63x45mm, as it's overall length is 45mm). Ballistics for this cartidige appear to be lost, but the .30 Carbine (7.62x33) would appear to be very similar in size (although the Mannlicher case is slightly bottlenecked rather than straight). It retained the same 6-round magazine capacity as the earlier Mannlicher carbines, but a larger magazine could easily have been made. Development was ended because, alas, Mannlicher perished in 1904.