The family of barrels for the M134D is the result of thousands of man-hours and millions of rounds devoted to testing and development. Because of these efforts Dillon has been able to reduce the End Users dependency on replacement barrels by doubling barrel life expectancy. The original GE designed barrel required replacement every 100,000 rounds.
The Dillon Barrel Group has a life of 200,000 rounds with barrel erosion gauging beginning at 125,000 rounds.
Dillon Aero produces three types of barrels for the M134 family, the Standard Barrel, Heavy Barrel, and the new, lightweight Short Barrel.
The Standard Barrel is an replacement/upgrade to the original GE production barrel. Dillon added an 1/8th inch of material to the diameter of the Standard Barrel making the taper consistent from breech to muzzle. The added material eliminates weak points that will fail when the barrels thermal limits are exceeded. Greater thermal resistance allows for longer firing times with greater resistance to barrel failure.
The newest barrel for the M134 is the Dillon Short Barrel. The Short Barrel measures 18 inches in length while the diameter remains the same as the Standard Barrel. This reduction in length provides a significant reduction in weight while having a negligible impact on accuracy or thermal limitations.
Weight: Each Dillon Short Barrel weighs 1.85 pounds. A full set of six is 11.1 pounds. Compared to the Standard Barrel set, which weighs 14.7 pounds, the Short Barrel set is 3.6 pounds lighter. A complete M134D-T with Short Barrels is 41.5 pounds. That is a significant reduction in weight.
Accuracy: The muzzle velocity of an M134D Standard Barrel firing NATO 7.62MM Ball is 2750 Fps (+/-). The muzzle velocity of the new Dillon Short Barrel using the same ammunition is 2680 Fps (+/-). This translates to a difference of about six inches in aimpoint at 500 meters and 22 inches at 1,000 meters.