The 5.56mm can't even penetrate a 0.05 inch thin metal planel from a distance of >25 meters. This is completely unrealistic since there are documented penetrations of 1/4 inch steel by 5.56mm cartridge from 200 yards with lower mass bullets than military grade NATO standard ammunition.
Edit: it seems the problem is not the cartridges but the materials trying to be penetrated. These include atleast the metal panels of the sheds and brick / concrete walls that won't let even a .50cal round penetrate fired from point blank. Even the 7.62 NATO should be able to punch through the walls from close enough. {F22685} {F22686} {F22687} {F22688} {F22689}