We took 7 AR15's to the range, with 7 different Barrels.  We loaded up 5 different decent loads, and ran those loads across 7 guns, using two different shooters.
Here is list of barrels we used:
Compass Lake Krieger 16" 1:7 Wylde
Compass Lake Douglas 18.1" 1:7 CLE
White Oak Armament (WOA) Predator 20" WOA Custom Chamber
WOA Shilen Rachet 20" 1:7.5 Wylde
Proof Research Carbon Fiber 16" 1:8 Wylde
Faxon Match Series Flame Fluted 18" Wylde
Colt 6920 LE (chrome Lined factory barrel)  16" 5.56
We used 5 loads to test with today
  1. Berger 55 Grain Match Target - Benchmark 25.0 grains 2.255 OAL Rem 7.5 new brass
  2. Sierra Match King 69 Grain - Norma 203B 25.1 grains 2.255 OAL Rem 7.5 new brass
  3. Berger 77 Grain OTM - Reloader 15 23.7 grains 2.255 OAL Rem 7.5 new brass
  4. Berger 77 Grain OTM - Vihtavuori N133 22.0 grains 2.255 OAL Rem 7.5 new brass
  5. Sierra Match King 77 Grain Moly - Norma 203B 24.0 grains 2.255 OAL Rem 7.5 new brass
(Norma 203B is virtually the same exact powder as Reloader 15, if not the same)
Testing method...
7 bullets loaded into every magazine.  First shot off target, then shoot 5 on target, then eject last, 7th bullet. So on the targets there is never a first or last shot out of the magazine.  For control.
Here is components used on the guns for the test. 
Compass Lake Krieger
Compass Lake Douglas
WOA Shilen Rachet
Proof Research Carbon Fiber
Faxon Match Series Flame Fluted
The above used Superlative arms PISTON SYSTEM.

Colt 6920 LE
White Oak Armament (WOA) Predator
These two used traditional GAS systems

Generally, if you ask a professional barrel manufacturer about PISTON system VS Traditional GAS impingement system they will say PISTON system degrades accuracy, and traditional GAS impingement is superior for accuracy?  Are they right?  We think they are probably right. But honestly, we are not competitive shooters.  The piston systems are so good, the gun runs so clean. 

More parts used:
Trijicon Accupower 5-50x56 Scope was used at 50x magnification @100 yards for ALL tests.  Detachable base, re-zeroed on each gun, each time.
All guns used match triggers at around 3.5 lbs of pull.  Such as CMC Single Stage 3.5, and Rise Armament RA-534, and Rise Armament RA-535
ALL GUNS were secured tightly in a Caldwell Leadsled DFT II

Shooter M Page 1

Conditions during test:
65 degrees
6 MPH Wind
Shooter M page 2
Conditions during test:
69 degrees
6 MPH Wind

The Colt absolutely hated the N133 berger OTM load.  We tried it on other paper, and it still was 4" groups, just randomly flying all over the place.
Shilen and Krieger performance was consistent.  AR15's have slight flyers, this is just normal.  Its not a bolt gun. 

Shooter M page 3
Conditions during test:
71 degrees
6 MPH Wind

We did not have super high expectations for the Proof, as you would not buy that for pure accuracy, it would not be good value overall.  However, it loved the Reloader 15 and the Berger OTM 77 grain.  It liked the 203B, with 69 grain SMK, but had 1 small flyer.
Shooter J page 1
Conditions during test:
75 degrees
8 MPH Wind
Shooter J page 2
Conditions during test:
78 degrees
8 MPH Wind
Again, we see Shilen consistent across the loads pretty much.  Shoots anything "good".  Krieger was lights out with a few loads.
Again, the Colt would not shoot the N133 77 grain OTM's at all.  BUllets flying all over the place.  We did a lot more than 5 shots, we did dozens, and it was 3-4" group no matter what shooter.
Shooter J page 3
Conditions during test:
79 degrees
8 MPH Wind
Top 25 out of the 70 loads
Top load, turned out to be our guess.  25.1 Grains of Norma 203B, 2.255 OAL using a 69 grain Sierra Match King.  Really good. 
Average across 5 loads with each barrel
WOA Predator was the only barrel that was sub MOA across all 5 loads with both shooters.  Krieger BARELY didn't make it.
Shooter M Data
Shooter J Data
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