Daniel Defense M4 Upper Review

We headed to the range with the upper receiver we built here.  This build was based on a Daniel Defense stripped M4 style carbine length gas system 16″ upper.  We added a Daniel Defense Lite Rail 9.5 FSP, Larue LT103 with CSAT rear, Daniel Defense chrome bolt carrier group, and a Aimpoint T1 with 2 MOA dot.

We mounted the upper on a lower equiped with a CTR stock and Wilson TTU-Mil trigger.

For our initial zero, we began at 7 yards with the CSAT iron sights using PMC 55 grain 223 ball ammunition.  Using the close range notch at the top of the rear sight, we fired one round at the top left black paster (target below) and made an initial adjustment.  We then fired another 5 round group into the same paster to check point of impact. Finally, we ended up bumping the rear sight left and firing 5 rounds at the right paster.  Moving back to fifty yards, we fired a 5 round group prone at the center of the CSAT target.  Note the line in the picture below showing the point of aim.

The first 50 yard group was a little lower then we preferred  so we added elevation to the front sight and fired the second group (shown above the line in the target below).  If you’ve never started your zeroing process at 7 yards, you are missing out.  With the AR style rifles, it is the place to start.  

Zeroing the irons.  The top left, then right pasters are used at 7 yards to get a rough zero.  At 50 yards, the zero can be further refined.  This technique saves a lot of time and doesn’t require a spotting scope.
Close up view of CSAT rear sight. The top notch is used for close range precision shooting, with the aperture is used for distance.

Remounting the 2 MOA T1 sight onto the rifle, we co witnessed the red dot to the irons on the bench and again moved to 7 yards.  Holding the dot on the center of the paster, we fired a five round group at the top left paster.  To gauge elevation, we utilize a 223 case to measure the distance between the point of aim and the point of impact.  At seven yards, when they are a case length apart, the elevation will be very close at 50 yards.  In the past we used to measure the distance from the POA to POI with a ruler, Bill Rogers mentioned this technique in his carbine DVD and we are sold.

Using a cartridge case at 7 yards to adjust the zero of the rifle. This is our initial group. We adjusted the T1 left and fired another group at the right paster at 7 yards to confirm our adjustment before moving to 50 yards.
Here is our zero after firing a total of 3, 5 round groups. The first two were fired at 7 yards, the third at 50. Notice the circle drawn into the target to show point of aim. We like to have the top of our dots centered in our groups to allow precision shots at distance. Using a 223 case works.

Moving to the 200 yard line we further refine our zero.  We like using the CSAT long range target for non magnified optics at distance.  We hold the top of the front sight and or dot at the bottom edge of the black line.   Here at the two inital five round groups fired at 200 yards.  All shooting is unsupported prone.  It’s pretty impressive how close you can get at 7 yards!  Keep in mind we made no changes to the optic at 50 and only one change to the irons (which was apparently a little too much).

Here are our initial 200 yard groups. The top left group is fired with irons, and the bottom right with the T1 2MOA. While a center mass hold (we held on the bottom edge of the black line) would have had rounds impact the target, further adjustments are made to dial in the zero.

With our iron and optical sights zeroed, we post a fresh CSAT target and begun to shoot Paul Howe’s CSAT standards.  If you are unfamiliar with his standards, we encourage you to check them out.  For each standard the shooter starts standing, facing down range, muzzle below the belt, eyes on target.  All rounds must impact inside the black center box.  Paul has par times posted on his site.  All of our shooting was within standards and below par, our times are posted below.

100 Yards, 5 rounds standing to prone: 10.89 seconds
75 yards, 5 rounds standing to kneeling: 17.33 seconds
50 yards, 5 round standing to kneeling: 13.93 seconds
25 yards, 5 round standing: 6.97 seconds
7 yards, 1 round standing: .91 seconds
7 yards, 2 rounds standing: 1.06 seconds
7 yards, 2/1 rounds standing: 1.64 seconds
7 yards, 2 rounds on 2 targets: 2.45 seconds
7 yards. 5/1 rounds standing: 1.99 seconds
Cleaning the CSAT standards with our upper!

Finally we collected some chronograph data for our upper using our excellent Magneto Speed barrel mounted ballistic chronograph.

PMC 55 grain 223 Remington 2691 fps, sd25
Winchester 62 grain OTM 5.56mm, 2896 fps, sd 30
Winchester 62 grain M855 5.56mm, 2986 fps, sd 24
The bayonet mounted reader used by the MagnetoSpeed chronograph. We love this thing.

Summary of findings:

  1. This was a nice, well balanced upper that provides shooters with the full range of capabilities in a compact package.
  2. If you haven’t begun zeroing at 7 yards, you are missing out.  It saves time and ammunition
  3. The T1 2MOA reticle is far more refined then the 4MOA model we are accustomed to.  At 200 yards, the dot still subtends 4″ as opposed to 8″, this difference is significant  We prefer the 2 to 4 MOA.
  4. The 9.5 FSP Lite Rail provides a the shooter the same firing grip as a mid-length rifle, without the need for mid-length parts.  While mid-length parts are becoming more standard, we know some shooters who try to avoid non standard rifle or carbine length gas system parts.
  5. Initially we selected an XS tritium front, but replaced it with a Trijicon front sight before we headed to the range.  On a carbine length gas system, a full turn of the sight is approximately 8 MOA (5 MOA on a rifle length system).  The XS sight only allows full revolution  or in this case, 8 MOA sight adjustments.  The Trijicon front sight has a different adjustment method that allows 2 MOA (1.25 on a rifle length system) sight adjustment.  While we may have gotten lucky and been able to get an acceptable zero with it, we found the XS front too coarse for our needs.  Additionally, the Trijicon front sight is narrower, .090″ as opposed to 1.005″ for the XS (factory is .069″).  In practice, the Trijicon front sight is roughly the same width as an IPSC target at 200 yards on a carbine length gas system.
  6. We used to be huge fans of the Vicker’s sling, but have run mostly VTAC for the past few years.  In the rush to test this we grabbed a Vicker’s sling, while we do like it, we absolutely prefer the VTAC.  Its easier to adjust and the thinner nylon material is slicker and slides across clothing easier.
To build your AR15 upper visit Brownells for the parts we used here: