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Old 09-04-2017, 11:27 PM   #1
Z09SS
 
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Default Statting 5.56x45mm ball; M855A1

M855 from a 14.5" M4 barrel is 4d+2 pi.

Despite the steel penetrator, it's not considered armor piercing.

This is mostly because the 600m distance to punch the DR 4 of a steel pot is well within the 800 yard 1/2D distance of the 5d pi from the 20" M16A2 barrel and the 750 yard 1/2D distance for the M4.

The minimum damage from both an M4 and M16A2 penetrate that helmet.

The 1/2D for M193 from an M16A1 is 500 yards, the minimum damage from 5d pi won't penetrate now.

With me so far?

From the physical description of the M855A1 bullet, it conforms to how High Tech describes TL6 Armor-Piercing (AP) ammo. That would change the damage to 4d+2(2) pi-. The problem with this is M855A1 appears to perform no better against armor or barriers than M855 and is comparable to M80 ball in tissue. pi- would be worse soft tissue performance than before when the reports are saying it's better.

7.62x51mm NATO M80 ball is 7d pi.

M855A1 fired from an M4 is reportedly doing comparable soft tissue damage to M80.

OK. Giving M855A1 hollow-point status brings the damage to 4d+2(0.5) pi+.

7d pi does 7-42 points of damage. 24 average.

4d+2 pi+ does 9-39 points. 24 average.

That is comparable.

The niggling problem now is the (0.5) armor divisor for going hollow-point. By all accounts, M855A1 doesn't behave differently than M855 against barriers or armor. (0.5) would give unarmored targets DR1 and would double the DR of armored targets.

Thus 4d+2(0.5) pi+ shouldn't penetrate the, now, DR 8 of a steel pot with minimum damage. Yet, it does.

The way the round appears to behave is 4d+2 pi+. Not sure what generic label to apply to it here though or what it should do to the cost per shot, especially since it's shaping up to be not a lot more expensive than M855.

This going to matter because they're applying this technology to 7.62 as well in the M80A1 round.

One way to explain it can come from M855 being the US version of FN's SS109, which was developed in the 1970's, and is thus a TL7 round, 1980 being the cut-year between TL7 and TL8. Thus M855A1 is a TL8 round.

There's only three TL8 kinetic energy bullet types listed in High Tech and they're all depleted uranium armor piercing rounds.

I think I shall call it:

Enhanced Performance Ball (EPB) (TL8)

This ammo is made from a hardened steel tip with a lighter metal core and is designed to cause more damage to soft tissues via tumbling and fragmentation, without sacrificing penetration against armor or barriers.

Change damage type: pi- becomes pi, pi becomes pi+, and pi+ becomes pi++ (no effect on pi++). Multiply CPS by 1.2. LC2.
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Old 09-05-2017, 07:11 AM   #2
DouglasCole
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Default Re: Statting 5.56x45mm ball; M855A1

I went through a similar process with the Mk318 alternative:

https://gamingballistic.com/2016/01/...m-mk318-mod-0/
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Old 09-05-2017, 08:46 AM   #3
clu2415
 
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Default Re: Statting 5.56x45mm ball; M855A1

What ammo was used to get 800 and 750 yard half damage ranges for the M16A2 and M4? What's your source for a 500 yard half damage range for M193?
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Old 09-05-2017, 09:39 AM   #4
Z09SS
 
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Default Re: Statting 5.56x45mm ball; M855A1

GURPS: High Tech 4th Edition is where I got the 1/2 damage ranges.

Page 117 for the M16A2, where it also mentions the change from .223 Remington to 5.56x45mm NATO.

Page 120 for the M16A1's range stats.

Page 120 for the M4A1's stats.

The M16A1 uses M193, the M16A2, M4 and M4A1 use M855.
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Last edited by Z09SS; 09-05-2017 at 09:44 AM. Reason: I did not realize we needed to academically source references here now.
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Old 09-05-2017, 10:30 AM   #5
clu2415
 
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Default Re: Statting 5.56x45mm ball; M855A1

One note is that the standard for M193 was a steel helmet at 500 yards and M855 required penetrating that helmet at 800 meters or 874 yards. GURPS M855 doesn't pass NATO standards!
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Old 09-05-2017, 10:54 AM   #6
Fred Brackin
 
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Default Re: Statting 5.56x45mm ball; M855A1

Quote:
Originally Posted by Z09SS View Post
With me so far?
From the physical description of the M855A1 bullet, it conforms to how High Tech describes TL6 Armor-Piercing (AP) ammo. That would change the damage to 4d+2(2) pi-. .
No. Per HT p.167 2nd paragraph under AP (TL6) you add a divisor of (2) but multiply damage by 0.7. That would change the damage to 3D(2) P-.

It is APHC that does full damage with the (2).
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Old 09-05-2017, 04:44 PM   #7
warellis
 
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Default Re: Statting 5.56x45mm ball; M855A1

M855A1 ballistic gel test: https://youtu.be/d8IvDPuVuho

M80A1 ballistic gel test: https://youtu.be/yW-jlvNQA8w

In real life, the M855A1 ball ammo is superior to M855 ball ammo due to much quicker, and more consistent, fragmentation when coming out of either 14.5-inch barrels, like those of the M4A1, or out of 20-inch barrels, like those of the M16A4.

It is less velocity dependent compared to the original M855 ball ammo.

http://www.thefirearmblog.com/blog/2...the-real-deal/
Quote:
TWC Tests M855A1: Yes, It’s The Real Deal

M855A1 is the Army’s new round; it boasts improved accuracy, penetration, and terminal effectiveness vs. the legacy M855 “green tip” round. We previously covered the story of M855A1, and Major Glenn Dean’s history of the round’s development, but how does it really perform? Fortunately, The Wound Channel has come into possession of some of the new ammunition, and put it to the test.

https://youtu.be/d8IvDPuVuho

If the above gel tests are representative, then the Army’s research and development has paid off. The round exhibited exceptionally short time to fragmentation, and deep penetration from the stable copper slug, with an added deviating wound channel from the steel “arrowhead” penetrating tip. That is certainly improved performance vs. M855, but unfortunately with only two shots into gel, the above video does not give us an idea of how true the Army’s claims that the M855A1 EPR is yaw independent are – though the very short neck before the breakup of the projectile does suggest it is fragmenting before any yaw is occurring.

As for penetration, The Wound Channel tested M855A1 against AR600 and AR680 steel plates, with the Enhanced Performance Round defeating both handily, even though they are both rated to stop the “semi armor penetrating” M855; the latter video is embedded below:

https://youtu.be/tMSNc3lZsYE

M855A1 has not been without its detractors, nor has it been free of its fair share of teething troubles, including issues with increased wear and tear on the rifles firing it, but it certainly seems to be a big step up in performance from legacy ammunition.

Last edited by warellis; 09-05-2017 at 05:01 PM.
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