An Accuracy Comparison of Three Different Barrel/Ammunition Combinations

[Molon]

An Accuracy Comparison
of
Three Different Barrel/Ammunition Combinations

For this article, I compared the accuracy (technically, precision) of three different barrel/ammunition combinations. The three different AR-15 barrel/ammunition combinations tested are as follows:

• Lothar Walther barrel / GECO 223 Remington 55 grain FMJ Target
  
  
• Lothar Walther barrel / GECO 5.56x45mm 55 grain FMJ
  
  
• Colt 16” HBAR / Wolf Performance 223 Remington 62 grain FMJ
  

The same 20” Lothar Walther barrel was used to test the two different GECO loads. This stainless-steel barrel has a 223 Wylde chamber and a 1:8” twist.







The 16” Colt HBAR used to fire the Wolf 62 grain FMJ ammunition is chrome-lined and has a 5.56mm NATO chamber with a 1:9” twist. This is the same barrel found on the Colt 6721.









All of the shooting for this article was conducted using my AR-15 bench-rest set-up. The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for.

Shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The barrels used in the evaluations are free-floated. The free-float handguard of the rifle rests in a Sinclair Windage Benchrest with the aid of a forend adaptor, while the stock of the rifle rests in a Protektor bunny-ear rear bag.

The same AR-15 lower was used to test all three of the different barrel/ammunition combinations. The lower houses a Geissele Hi-Speed National Match trigger.

Sighting is accomplished via a Leupold VAR-X III set at a magnification of 25X and adjusted to be parallax-free at 100 yards. A mirage shield is attached to the objective-bell of the scope. Wind conditions on the shooting range are continuously monitored using a Wind Probe. The set-up is very similar to that pictured below.

















The Wind Probe.








Atmospheric conditions on the range are monitored and recorded using a Kestrel 4000 Pocket Weather Tracker.







Prior to shooting the factory loaded ammunition, control groups were fired using match-grade hand-loads. The radial dispersion of the control groups was significantly smaller than that of the factory loaded ammunition.



...






A 3-shot group of the GECO 223 Remington 55 grain FMJ Target ammunition was fired from the Lothar Walther barrel at a distance of 100 yards. This group had an extreme spread of 0.47”







...







A 3-shot group of the GECO 5.56x45mm 55 grain FMJ ammunition was fired from the Lothar Walther barrel at a distance of 100 yards. This group had an extreme spread of 0.46”







...









A 3-shot group of the steel-cased, bi-metal jacketed, Wolf Performance 62 grain FMJ ammunition was fired from the Colt 16” HBAR (6721) barrel at a distance of 100 yards. This group had an extreme spread of 0.47”










Part Two




Looking at the 3-shot groups above, you might be misled into believing that the precision of the three different barrel/ammunition combinations is virtually identical. However, according to ballistipedia.com, the use of 3-shot groups for evaluating precision “is statistically almost meaningless.”


http://ballistipedia.com/index.php?t...bing_Precision



Now, if instead of using “statistically almost meaningless” 3-shot groups, we follow the practice of the US Army Marksmanship Unit for evaluating the precision of AR-15 barrel/ammunition combinations and shoot three consecutive 10-shot groups, a much different picture emerges when comparing the precision of the three different barrel/ammunition combinations being evaluated; particularly if we over-lay the three 10-shot groups on each other to form a 30-shot composite group and use the more statistically powerful mean radius to compare the radial dispersion of the three different barrel/ammunition combinations.



Three 10-shot groups of the GECO 223 Remington 55 grain FMJ Target ammunition fired in a row from a distance of 100 yards from the Lothar Walther barrel produced the following extreme spreads:

1.71”
1.06”
1.52”

for a 10-shot group average extreme spread of 1.43”. The three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for the 30-shot composite group was 0.47”.





Three 10-shot groups of the GECO 5.56x45mm 55 grain FMJ ammunition fired in a row from a distance of 100 yards from the Lothar Walther barrel produced the following extreme spreads:

2.55”
2.09”
2.19”

for a 10-shot group average extreme spread of 2.28”. The three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for the 30-shot composite group was 0.79”.





Three 10-shot groups of the Wolf 62 grain FMJ ammunition fired in a row from a distance of 100 yards from the Colt 6721 barrel produced the following extreme spread:

4.23”
4.29”
3.68”

for a 10-shot group average extreme spread of 4.07”. The three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for the 30-shot composite groups was 1.22”.





The 30-shot composite groups . . .






. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


The 10-shot control group fired from the Lother Walther barrel for the GECO 223 Remington 55 grain FMJ Target ammunition test . . .







The 10-shot control group fired from the Lothar Walther barrel for the GECO 5.56x45mm 55 grain FMJ ammunition test . . .








The 10-shot control group fired from the Colt 6721 barrel for the Wolf Performance 62 grain FMJ ammunition testing had an extreme spread of 0.89”.






....

[JGifford]

Try Wolf 55gr "Black Box". Shoots pretty well for me. This is just with a Nightforce 1-2 and a CHF/Chrome-lined .gov barrel over a sandbag. I am betting you could do even better with your rig.