This Upper is essentially new, only used with scope to test the Anderson Multi-Cal Lower. Maybe 10 rounds, so the barrel will need to have proper break-in completed. Shot extremely well, 1MOA @ 100yds with good brass ammo. - Upper is compatible with any Multi-cal lower. - Has a 16" Forged 7075 T6 receiver, barrel is 1:8 twist standard contour Nitride coated 4150 Chrome Moly Vanadum with BCA long flash hider. - BCG is Nitride coated 9310 Steel, standard Charging Handle. - Full length M-Lok Picatinny rail with carbine length low profile gas block.