I’ve had several customers inquire about specifically what type of steel is used in our black phosphate, chrome lined gun barrels. The following should help clarify.
Windham Weaponry uses a modified 4150 Vanadium steel, better known as MIL-B-11595E CMV. Some manufactures call this “4150Mod”. Our barrel steel is not plain “4150”. Described better, it is a CrMoV steel based on the composition of 4150. The addition of Vanadium to the composition greatly increases the impact strength of the steel. Vanadium is used for grain refinement and the enhancement of mechanical properties. The material we use is identical to the material that the military and most other high end manufacturers use.
In these barrels we offer two different twist rates, 1-9 and 1-7. The 1-9 being the most popular. The 1-9 twist is generally good for stabilizing bullets from 45-69 grains. The 1-7 is best for 50-80 grain bullets.