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Big Army Changes Barrel Wear Criteria for M855A1 Ammo

This is a discussion on Big Army Changes Barrel Wear Criteria for M855A1 Ammo within the M16 AR15 forums, part of the Rifle Forum category; Originally Posted by Red Leg I hate to be a Debbie Downer, but nobody has stated the obvious here. With a 5.5 MOA it will ...


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Old March 8th, 2017, 02:51 AM   #16
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Originally Posted by Red Leg View Post
I hate to be a Debbie Downer, but nobody has stated the obvious here. With a 5.5 MOA it will cost soldiers there lives. Every enemy combatant that is shot at and missed he is still in the fight. You better believe I will be firing a letter of to my Congressman tomorrow with my concerns.
We've covered this, M855A1's accuracy requirements are no worse than the M855, or the older M198.

And while we're here, the accuracy requirements for M80 Ball:

Quote:
The average of the mean radii of all targets of the sample cartridges, fired at 600 yards, shall be not greater than 5.0 inches for ammunition scheduled for packaging in cartons or clips and shall be not greater than 7.50 inches for ammunition scheduled for packaging in links.
A mean radius of of 5.0 inches at 600 yards means 99.6% of all rounds fired must fall within a circle with a radius of 30 inches at 600 yards.
If you shoot 100 rounds of M80 Ball, at 600 yards, a minimum of 68 rounds will be inside a 20 circle, and no more than 4 rounds will be outside a 30 inch circle.

For 100 rounds of M193, M855 and M855A1 Ball fired at 200 yards, a minimum of 68 rounds will be inside a 7.2 inch circle and no more than 4 rounds will be outside a 14.8 inches. Ball ammo has never been the most accurate stuff.

To put it in perspective, we won World War II with ammo that was half as accurate; Caliber .30, AP, M2 was only required to have a mean radius of 10 inches at 600 yards.



Last edited by lysander; March 8th, 2017 at 03:48 AM.
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Old March 8th, 2017, 02:55 AM   #17
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This came out in a Maintenace Message from TACOM (Tank Automotive Armament Command) this week, complete with graphics. If you don't have a Common Access Card, you can't access the website. If I can remember until tomorrow, I'll PM you some info.

Edited to Add: No, I won't PM it to you, as it's marked For Official Use Only. I'm too old to have to hide out in Russia like Edward Snowden.
Don't worry, it will probably be in next month's P.S. Magazine . . .

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Old March 8th, 2017, 03:26 AM   #18
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Don't worry, it will probably be in next month's P.S. Magazine . . .
Or SHOOTING TIMES, or AMERICAN RIFLEMAN.

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Old March 8th, 2017, 09:31 AM   #19
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That's not how a throat gauge works....

The gauge has a ever so slight taper on the end, so the further it goes in the larger the hole. How far and what size hole depends on the taper.

2-1/4 inches may only be another thousandths of an inch or so.
Is there an easy way to equate the "thousands or so" into rounds fired ?.... or maybe a better way to say it would barrel erosion past the throat ?

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Old March 8th, 2017, 11:59 AM   #20
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Is there an easy way to equate the "thousands or so" into rounds fired ?.... or maybe a better way to say it would barrel erosion past the throat ?
What the erosion gauge in measuring of the diameter of the freebore and the diameter of the rifling at the origin of the rifling, as these get larger, more gas will escape passed the bullet. Accuracy, may or may not, be affected.

The Army has been trying to do that for years, without much luck.

Rate of fire, particular steel qualities, exact propellant types fired, etc., etc., make it a fools errand.

They just figured you stick the gauge in the barrel, and when it passes the NO-GO mark, and you probably have a barrel that will not maintain the spec velocity.


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Old March 8th, 2017, 12:14 PM   #21
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The Army is in denial. The new ammo is running at higher pressures and it going to mean they are going to have to change barrels more often and at lower rounds counts.

The new rounds is finding success on the battlefield, but barrel life is not going to be extended with this new round. DOD can issue all the new memos the want, it isn't going to happen.

The M4A1 has a much heavier barrel and that is a good thing, but I don't think they are going to get the lifetime out of that barrel running this ammo. Same is true of the 7.62 rounds.

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Old March 8th, 2017, 01:56 PM   #22
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It seems the USMC was on to something when they rejected the M855A1, back in 2009.

From the Marine Corps Times in re to the Marines being forced to adopt the M855A1, for standardization purposes.

"Marine Corps officials say they do not oppose the idea, provided the Army has fixed its round’s propensity to wreak havoc by causing excessive wear on a weapon’s inner workings.

The problem stemmed from the M855A1’s high chamber pressure and exposed steel tip, which could chew up a weapon’s feed-ramp, erode barrels and crack bolts, said Col. Michael Manning, the program manager for Infantry Weapons Systems at Marine Corps Systems Command in Quantico, Virginia."

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