When U.S. Army shooters twice fired public demonstrations of the new round, they did not employ standard 1:7-inch twist M16A2s or M4s, but accurized, match-grade, stainless-barreled rifles from the Army Marksmanship Unit (AMU). I contacted the AMU and learned that these rifles did not have standard-issue 1:7-inch barrels, but most likely 1:8-inch twist, which probably accounts for their “match-like” accuracy.
The downside of the new propellant formulation is, unfortunately, a commensurate increase in chamber pressure, which eventually will affect a rifle’s performance.
For gas port pressure, the M855A1 generates 50 percent higher pressure (23,767 p.s.i.) on the Special Ops 11.5-inch M4 barrel, compared to the 16,067 p.s.i. with the M16A2’s 20-inch barrel. That has been shown to cause port erosion, which boosts the automatic-fire rate, increasing the likelihood of jams. In the 2011 tests of new Army carbine prototypes, the barrels experienced “accelerated bolt wear” from firing the M855A1, because of higher chamber pressure and increased bore temperatures. A Special Operations Command test saw cracks appear on locking lugs and bolts at the cam pin holes on average at 6,000 rounds, but with as few as 3,000 rounds of “intense” full-automatic firing. The solution may be to find a means to count the number of rounds a rifle has fired.
Accuracy was not an issue until well into the cartridge’s final development. Despite America’s military forces being seven years into war, a 2008 PowerPoint briefing listed the M855A1’s first consideration as “Environmental Compliance,” while “Accuracy” merely followed. And then, when the new M855A1’s accuracy specifications were published, they were the same as the old M855 it replaced-a “standard deviation of 6.8 inches at 600 yards”-meaning at least half the bullets must impact within 6.8 inches of the point-of-aim. That was quite at odds with, “match-like accuracy.”
A civilian Army Marksmanship Unit (AMU) shooter demonstrated the M855A1’s accuracy at the NRA’s 2012 Camp Perry National Matches. He did not fire a standard M4 or M16A2 with a 1:7-inch twist barrel, however, but instead shot a match-grade rifle with a stainless barrel and a more accurate 1:8-inch twist. Thus, the demonstration proved nothing. Likewise, another Army demonstration pitted the old M855 fired by a standard M4 Carbine against the new M855A1 fired by an AMU match-grade rifle, and again, any results were skewed by different barrel-twist rates.
And then, when the new bullet’s ballistic gelatin tests were completed, the Army classified the results. “What’s so secret?” a firearm industry expert asked me. “It’s just ball ammunition.” One Army officer wrote that the classification was, “so the process does not lend itself to adoption by commercial entities.” However, a Picatinny Arsenal representative told me it was classified, “to preserve our technological advantages over our potential adversaries.
Performance assertions were skewed, too. While developers hailed the new bullet as “vastly better” at penetrating steel than the 7.62 mm, M80 ball round, this was an apples-to-oranges comparison. The M855A1 has a steel penetrator-it should penetrate better than a 7.62 mm ball round, which contains a lead-alloy core. Similarly, it was misleading for the Army Research Laboratory to have tested the round, “against 24 layers of Kevlar fabric out to 1,000 meters.” That thickness of Kevlar is only rated to protect its wearers against handgun ammunition-not rifle ammunition-and especially not a rifle round with a steel penetrator. Such a claim was both irrelevant and disingenuous.
From the guy who has presented no data, that's chutzpah...