Overview of the Daniel Defense M4A1 AR-15 Upper Receiver
The M4A1 AR-15 upper receiver from Daniel Defense is a premium quality component that will perform as expected. Daniel Defense makes all of their components in house and holds there part to the highest standards.
The upper receiver used for this assembly has CNC machined internal surfaces. The receiver is made from high quality, aircraft grade 7075-T6 aluminum. This type of aluminum is far superior and stronger to the 6061 aluminum used in some competitors upper receivers. For such a vital component, the 7075 aluminum is really ideal. The aluminum is finished with a type II hard coat anodizing.
The 5.56x45mm chambered barrel is formed from chrome moly vanadium steel. As opposed to being cut, the barrel is formed by a cold hammer forging process. The cold hammering process makes for an extremely consistent product that will give you repeatable results. The barrel has a 1:7 twist rate, which is preferred for heavy projectile weights. To increase the longevity and easy of maintenance, the internal surface of the barrel has been chrome lined. The barrel is 14.5” inches in length with a M4 barrel profile. However, this upper will not make your rifle an SBR, as it has a permanently attached pinned and welded muzzle device that extends the overall length of the barrel to greater than 16”, thereby conforming to NFA laws. The barrel has a black heavy phosphate coating.
As with all current Daniel Defense Upper receivers, this upper utilizes a direct impingement gas system. Since this upper has a relatively short, 14.5” barrel and then a permanently attached muzzle device, the gas system utilized in this upper is carbine length. The carbine length gas system is the most widely chose gas system length in the military and has an excellent track record for reliability. A low profile gas block is used in order to fit under the rail system. The gas block is pinned into place to prevent any inadvertent movement. To ensure that the gas block is capable of putting up with significant stress, the gas block was machined from 4140 hardened steel and then finished in a mil-spec heavy phosphate coating.
The muzzle device for this upper receiver is permanently attached to the 14.5 inch barrel to make for an overall length greater than 16 inches. A Daniel Defense extended flash suppressor is the muzzle device chosen for this upper. It is formed from 17-4 PH Stainless steel and finished with a salt bath nitride, giving it a black appearance.
Bolt Carrier Group
The bolt carrier group used for this Daniel Defense Complete upper is a full mass M16 profile bolt carrier. The BCG has been MP tested and is chrome lined. The gas key has been properly staked in place to prevent any screw walk out.
Daniel Defense first gained popularity from their AR-15 railed hand guards. They are known for being some of the best in the industry. Included with this complete AR upper is a Rail Interface System (RIS) II rail system. This hand guard provides the user with four full length Picatinny rails on all four sides of the hand guard for the attachment of various accessories. This rail is machined from 6061 T-6 aluminum and finished in an FDE color via hard coat anodizing.
This upper receiver package comes with Sanoprene rail panels. These panel are heat resistant to 300 degrees Fahrenheit to be able to withstand heavy, sustained firing. They will offer basic protection to your rail and make for a more comfortable gripping surface when firing.