More information on the differences in DSG's Duty, Utility and Precision Series barrels.
Our Duty and Precision barrels differ in a few key ways. Read below for details about each type.
Note: DSG barrels that are assembled in our complete uppers are drilled for gas block mounting by our armorers. If you are purchasing a DSG barrel for a DIY build, we recommend a barrel dimpling jig or allowing a certified armorer to provide this service for you. We do not recommend fielding any weapon without a dimpled or pinned gas block.
Duty Series barrels are designed with high heat, high round count use in mind. They are constructed from 4150CMV steel. CMV is short for chrome moly vanadium and 4150 refers to the grade of steel. Alloy steel like 4150CMV incorporates different elements (Sulphur, Silicon, Carbon, etc.) added to the make-up of the steel to produce a barrel that is strong and also allows it to be easily and accurately machined. Once the barrel is properly heat treated it also allows the barrel to function reliably under extremely high pressures. 4150CMV also incorporates a high chrome content. This chrome content in the steel adds substantial strength to the finished barrel, but does not add adequate corrosion resistance by itself.
For additional corrosion and wear resistance our barrels are then QPQ coated. QPQ stands for 'quench polish quench'. The QPQ process is essentially a chemical case hardening procedure that is applied at 1000f. QPQ coating barrels allows for an extremely hard, corrosion resistant finish that also provides great wear resistance during the barrel's life cycle. Duty series barrels also incorporate a nickel boron coated barrel extension for lubricity, corrosion resistance and long wear life.
Our standard twist rate for Duty Series Barrels is 1:7. While we also test with 55gr 5.56 ammunition with results that exceed the mil-std, many of our customers use heavier bullets up to and including 77gr. The 1:7 twist allows these heavier projectiles to stabilized for maximum performance.
Chambers are generally 5.56mm in Duty Series Barrels (refer to each SKU's individual description to verify).
Precision Series barrels are produced with accuracy as their foremost design goal. Made from 416R stainless steel, Precision Series barrels can provide an overall accuracy advantage of 20-30% when used with good quality, factory loaded, match grade ammunition. Precision barrels are guaranteed for 1MOA or greater accuracy with match ammunition (3 shot groups at 100 yards). In practice we've found their accuracy to be even better, but extreme accuracy can be dependent on other factors beyond our control (shooter, environment, ammo choice, build quality, etc.).
416R stainless steel as used in our Precision Series barrels has a higher chrome content than other barrel materials allowing it to be corrosion resistant without additional coatings being required. Its material makeup also allows it to be highly machineable which provides for a smooth and consistent surface for the bullet to travel. Stainless steel also has a lower overall pressure rating than other materials like 4150CMV. Stainless steel can be more susceptible to heat damage at lower temperature levels. Although this should only be a concern with high round count use without allowing the barrel to cool properly.
In our Precision Series barrels we generally use the 223Wylde chamber specification and a 1:8 twist rate (see each individual SKU for exact specifications). Precision Series barrels also include a Nickel Boron coated barrel extension for corrosion resistance and positive feeding. 11 degree Target crown is standard.
Utility Series Barrels are currently produced with the same 4150CMV steel as our Duty Series barrels and are also QPQ coated in the same manner. With cost savings in mind, Utility Series barrels include a standard M4 barrel extension that is coated along with the barrel and a flat muzzle crown. When used in DSG complete uppers Utility barrels are usually not test fired, but are assembled and quality checked in the same manner otherwise.
In general the Utility Series is used for any opportunity we have to pass along a less expensive, but high quality alternative to our Duty and Precision grade barrels and uppers.