The Firearm Blog TV does a comparison of two popular compact firearms, the H&K MP5 and the B&T APC-9... "Two of the best pistol caliber carbines in the game: The LEGENDARY Heckler & Koch MP5 faces off today against the B&T APC-9. The H&K MP5 has been the gold standard for PCCs or SMGs for nearly 60 years, while the B&T APC-9 is newer, having been invented by the Swiss group Brugger & Thomet in 2011.