What type of gun was attempted to improve in The Heckler & Koch MP2000?
Heckler &amp; Koch MP2000 The Heckler & Koch MP2000 was an attempt to improve the MP5 series. Prototypes of the gun showed similarities to the UMP. An interesting feature of this gun was that it featured a silencing system which prevented the bullet from reaching supersonic speeds by venting some of the propellant gases. The gas vent hole could be closed in order to achieve normal bullet velocities.
.30-40 Krag The .30-40 Krag (also called .30 U.S., or .30 Army) was a cartridge developed in the early 1890s to provide the U.S. armed forces with a smokeless powder cartridge suited for use with modern small-bore repeating rifles to be selected in the 1892 small arm trials. Since the cartridge it was replacing was the .45-70 Government, the round was considered "small-bore" at the time. The design selected was ultimately the Krag–Jørgensen, formally adopted as the M1892 Springfield. It was also used in M1893 and later Gatling guns.