Barrel Steel is Certified MIL-B-11595E Chromoly Vanadium Alloy and Magnetic Particle Inspected they are also stress relieved.

Mil-Spec M4 Barrel Extension with MIL-STD-171 Phosphate Finish MIL-STD-171 Hard Chrome Chamber
1/7 Twist Rate MIL-STD-171 Hard Chrome Bore
5.56mm Nato chamber
All Chambers are Individually Checked for Head Spacing Before and After Plating
All Barrels are Individually High Pressure Tested (HPT) and then Individually Magnetic Particle Inspected (MPI) MIL-STD-171 Phosphate Finish on the Barrel Exterior
1/2×28 Thread Pitch
Threads are Cut Concentric to the Bore
Uses 0.750″ Gas Block
Weight is 28.0oz
Spike’s Lifetime Warranty