Heavy metal's measure of grandiosity goes full tilt on the Periphery

While today's alt-rock can be excessively unassuming, heavy metal has retained a good measure of grandiosity. Periphery, the Bethesda-based sextet that headlined a four-band show Friday night at the Fillmore, recently released not one but two albums: "Juggernaut: Alpha" and "Juggernaut: Omega," whose titles suggest an A-to-Z survey of contemporary progressive metal.