För ett tag sedan så testade Us army hur olika Ak mådde efter att ha utsatts för sand och damm, i testet ingick: Colt M4, HK 416, FN SCAR-L, HK XM-8.
Saxat från en artikel från DID:
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The tests will include the M4 and 3 other rifles: the M4-based HK416, the FNH USA-designed Mk16 SOCOM Combat Assault Rifle (best known as FN SCAR-L), and the H&K XM8 carbine. Unlike the M4, the HK416, XM8, and FN-SCAR all use gas-piston operating systems to achieve automatic fire. The XM8 family is an very updated version of the popular G36 in use with many NATO militaries; it was slated to be the M4's replacement, but that RFP was suspended by the Army in July 2005 and then canceled in October 2005. The FN-SCAR is a "live" program, and July 2007 marked the beginning of Special Operations Command's operational tests of the FN-SCAR 5.56mm Mk16 and the 7.62mm Mk17, which could become its future mainstays.
Miltary.com reports that the US Army sand tests will include 10 samples of each weapon through which engineers will fire 6,000 rounds. Each weapon and loaded magazine will be exposed to "extreme dust" for 30 minutes then test fired with 120 rounds. Each weapon will be wiped down and lubricated every 600 rounds, with a full cleaning every 1,200 rounds. The firing, collection of data and analysis of data is expected to take approximately 5 months.
One's first reaction upon seeing the proposed testing regimen is to compare it very unfavorably with the regimen Delta Force put the HK416 through, firing it day after day without maintenance for thousands of rounds. Or even the testing HK itself uses for its HK416s. Indeed, it seems on its face to be a test designed to minimize the very weaknesses in the M4 incumbent that have triggered this controversy. Those who believe the cycle is reasonable cite 300 rounds as the soldier's 1-day load, and say that under sand storm conditions, a once a day wipedown is the bare minimum for any weapon. Every 600 rounds is thus a safety factor of 2 against the worst possible conditions. Of course, sandstroms have a way of lasting more than one day, and when they do – as in the initial portion of Operation Iraqi Freedom – even vehicle interiors may feature a fine particulate haze.
Within its chosen regimen, there are 3 key ways the Army may choose to bias the test. One is the size of the particulate in the dust chamber – which can be made large in relative terms to lower the number of problems with fouling and jams. The biggest problems in theater are with the very fine particulates. This is especially relevant given the October 2004 report prepared by the Desert Research Institute for the US military. "Geochemical and Physical Characteristics of Iraqi Dust and Soil Samples" stated that:
"....current chamber test methodology misrepresents real-world conditions. The character of the soils and dust collected from areas of military activity in Iraq is greatly different from the material used in current weapons testing procedures. Current procedures employ laboratory generated dust that is 99.7% silicon dioxide (i.e. quartz), contains no salt or reactive chemicals, and contains coarser particle sizes than most of the Iraq samples. Use of this material cannot simulate conditions in Iraq that have contributed to the weapons failures."
The next item to watch is whether the rifles used are randomly chosen, or cherry picked and then pre-maintained to perform at an unusual reliability level vs. a field weapon. A third way of gaming the testing system involves the level of lubrication used. One source noted that the first dust test new M4s had 9,836 jams in 60,000 rounds – almost one jam every 6 rounds. The Army kept working on the test until they figured out a "generous lubrication" approach that used far more than the manufacturer recommended, but lowered jams to 1 in 88 rounds. A fair test must match the manufacturer's manual for each weapon, or use the same lubrication for each weapon based on the minimum recommended among all test weapons.
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DID obtains some exact results from the Army's testing. The Army has now done three dust tests. In the late 2006/Jan 2007 report "Baseline Reliability and Dust Assessment for the M4, M16, and M249," the M4 jammed 9,836 times – 1 jam every 6 rounds. In a May 2007 "Extreme Dust Test II", with no competitors, the M4 had 1 jam every 88 rounds, using heavy lubrication. In the November 2007 "Extreme Dust Test III", as DID has discussed, the competing rifles were subject to significantly more maintenance and lubrication than elite American forces like Delta used in their weapon selection process, or indeed in HK's own field testing of its HK416s prior to shipment.
We'll begin with the Army's overall results, from its own release:
"Even with extreme dust test III's 98.6 percent success rate there was a total of 863 class 1 and 2 weapon/magazine stoppages with 19 class 3 stoppages. During extreme dust test II conducted during the summer, there were 296 total class 1 and 2 stoppages and 11 class 3 stoppages.
A class 1 stoppage is one a Soldier can clear within 10 seconds; a class 2 stoppage is one a Soldier can clear, but requires more than 10 seconds; and, class 3 is a stoppage that requires an armorer to clear."
DID will simply point out that 10 seconds can be a rather fatally long time when people are shooting at you, and at your friends. So, what happens when the Extreme Dust Test III stoppages are broken out by weapon?
The M4 Carbine is the Army's existing weapon.
882 jams, 1 jam every 68 rounds, again using heavy lubrication. In addition all 10 of the M4 barrels needed to be replaced, and a number of their parts were replaced during the test. None of the cold hammer forged HK416 and XM-8 barrels needed replacement.
The HK416 is a modified M4 carbine, which can be and has been converted from existing rifles. Used by US Special Forces.
233 jams, 1 jam every 257 rounds, 3.77x more reliable than the M4.
FN SCAR is US special Forces' new weapon, designed by SOSOCM. It just went into production in late 2007.
226 jams, 1 jam every 265 rounds, 3.85x more reliable than the M4
XM-8 is a developmental rifle. It's an advanced version of HK's G36, a rifle in wide use by many NATO armies. The US Army cancelled the XM-8 weapons family 2 years ago.
127 jams, I jam every 472 rounds, 6.95x more reliable than the M4.
The failure of M4 barrels at 6,000 rounds confirms SOCOM objections that date back to the Feb 23/01 report "M4A1 5.56mm Carbine and Related Systems Deficiencies and Solutions," which ended up concluding that "M4A1 Carbine… does not meet the requirements of SOF." The barrel replacement also increases the rifle's life cycle costs when compared with the 10,000 round advertised barrel life, as additional barrels are sold to the Army for $240 each. A longer, heavier M16 barrel, which is a competed production weapon, cost $100 by comparison. While the dust test is indeed an extreme test, the 10,000 round requirement is under "all conditions" – not just ideal conditions.
Dec 18/07: The US Army publishes "M-4 Carbine Has High Soldier Confidence Despite Test." Not exactly a headline to inspire confidence, as the Army acknowledges that the M4 Carbine finished last among the 4 contenders – but amazingly, asserts that the rifle is just fine and shows no interest in buying even the HK416's parts swap-out into the existing M4:
"After being exposed to the heavy dusting, 10 of each weapon fired 6,000 rounds apiece. They were fired in 50 120-round cycles. Each was then wiped and re-lubricated at the 600 round mark. After 1,200 rounds were fired from each weapon, they were fully cleaned and re-lubricated… "While the M-4 finished fourth out of four, 98 percent of all the rounds fired from it went off down range as they were supposed to do," Brig. Gen. [Mark] Brown [commander of Program Executive Office Soldier and the Natick Soldier Systems Center] said. "However, the three other candidates did perform better at about a 99 percent rate or better, which is a mathematically statistically significant difference, but not an operationally statistical difference.".... The Army has put an option on an existing contract for 64,450 M4s, according to the general."
"A mathematically statistically significant difference, but not an operationally statistical difference." Perhaps the US Army could put that on their recruiting posters, next to a picture of a jammed rifle.
Källa:
The USA's M4 Carbine Controversy