This is what 2A Armament says:
 
 
You asked for it, we made it.  Introducing our 2A Armament designed, lightweight 20" 6.5mm Creedmoor barrel.  This barrel will ship standard with our Xanthos XLR-20 rifle but is also available for individual purchase.

Features:

    4150 Barrel steel with QPQ Nitride
    6.5 Creedmoor SAAMI Chamber
    Length 20"
    Rifle-length gas system .091 gas port
    1:8 twist, 5R rifling
    5/8-24 muzzle thread (.625 thread length)
    .750" diameter gas block journal
    11 deg target crown
    LR-308 (DPMS Compatible) extension
    Weight - 2 lb 3.4 oz