This papercraft is a RG-6, a Russian 40 mm semi-automatic, 6-shot grenade launcher developed between 1993 and 1994 by TSKIB SOO, the paper model created by X.Diem. The RG-6 was required to increase the firepower of the infantry during urban combat, seen in small-scale conflicts, such as the Chechen wars. The RG-6 entered limited production by the mid-1990s and is now in use by various elements of Russian Army and special forces such as those in the MVD.
RG-6 is designed to fire all standard 40mm "caseless" grenades, available for the general issue GP-25 underbarrel launcher. The design of the RG-6 is, apparently, heavily influenced by the South African Milkor MGL grenade launcher, with some differences. The key difference is that RG-6 uses "caseless" rounds,and thus its cylinder is loaded from the front. The "barrel" is, in fact, a smoothbore tube, which served only as a support for front grip and sights.
The double-action only trigger unit is also modified from GP-25, with manual safety and several automatic safeties.
The cylinder is rotated using clockwork-type spring, which is manually wound during reloading. For reloading, the front cylinder plate with the "barrel" tube is unlocked from the frame and then rotated sideways, to expose the front of the cylinder. Each chamber in the cylinder is a separate muzzle-loading rifled barrel, similar in design to the GP-25 barrel.
The sights are folded for more convenient carry and storage, with a ladder-type rear sight. The buttstock is fitted with a rubber recoil pad, and when it is not in use, it is telescoped into the frame. [Source: wiki]