Milestones (Mountain Fever, 2018)

Bluegrass music has been on a growth spurt for a decade or more, and with that comes diversity that brings talk of what's 'real' bluegrass or who's more 'traditional.' Falling squarely in the middle of that argument is Volume Five, five guys who can play it straight, twangy and driving bluegrass style or throw it in a lower, sentimental country gear and wrench every drop of emotion out of a lyric.

About half of the group's latest looks back to Flatt & Scruggs and the Osborne Brothers, from the driving tempo of "I'll Turn My Back" to the spirited version of "The Lonesome Cry of the Whippoorwill," tunes that will have the most hidebound traditionalist smiling within a few bars. Elsewhere, however, they fall into more contemporary Mountain Heart style balladry on the treacly "Hayley" and try on a bluegrass take of the Creedence Clearwater Revival classic "Looking Out My Back Door."

The risk in diversity is always that one loses focus, but the players in Volume Five are in command of their various instruments. Every track features spotless picking and stellar vocal harmonies, two must-have elements for any respectable bluegrass band, but they never let the s