Feb 03, 2012 ยท H&K's HK 45 LEM makes a great duty or home defense gun. The new Heckler & Koch HK45 LEM is based on the firm's USP pistol and was originally designed to meet requirements of the U.S. Military Joint Combat Pistol program. The most obvious change from the USP is the use of a more ergonomic polymer grip with interchangeable backstraps.. "/>Usp 45 vs hk45