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Attack of the (M193) Clones, Part Two: M855 Comparison. (Page 1 of 2)
Posted: 12/12/2010 9:23:43 PM EDT
[Last Edit: Molon][Edited]
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Attack of the (M193) Clones, Part Two: M855 Comparison.
This thread is dedicated to Zhukov, for his tireless efforts in improving the signal to noise ratio in these technical forums. 
In Attack of the (M193) Clones, part one, we examined the velocity and accuracy (technically precision) of four different M193 clones currently available on the commercial market. In part two, we’ll be examining the velocity and accuracy of four different M855 clones currently available on the commercial market. The M855 clones examined for this article are shown below. IMI M855 
Winchester Ranger M855 
Prvi Partizan M855 
American Eagle XM855 
The obvious difference between the projectiles used in M855 and M193 clones is the weight difference of 7 grains, 62 grains versus 55 grains. The M855 projectile has a FMJ construction but also has a steel “penetrator” in the ogive section of the bullet. This makes the projectile unusually long for its weight, as well as giving it a lower specific gravity. Most, but not all, of the M855 clones have the tip of the bullet painted green. M855 versus M193 projectiles. 
The 62 grain M855 projectile is actually longer than the heavier 69 grain Sierra MatchKing. 
Note the steel penetrator in the sectioned projectile below. 
Chronographing of the M855 clones was conducted as described in part one, using the same 20” M16A2 barrel. The results are shown in the table below. 
Accuracy testing of the M855 clones was also conducted exactly as described in part one, using the same free-floated 16” Colt HBAR fired from my bench-rest set-up at 100 yards. As previously stated, I chose a chrome lined, NATO chambered barrel as the accuracy test vehicle as this is the type of barrel that these clone loads are most likely to be fired from. It is sometimes possible to obtain slightly better accuracy from mil-spec/NATO pressure loads by firing them from an AR-15 that has a stainless steel match-grade barrel with a hybrid chamber such as the Noveske NMmod0 chamber or the Wylde chamber for examples; but you're not going to make a silk purse out of a sow’s ear. Three 10-shot groups of each load were fired in a row with the results shown in the table below. 
Here are the previous accuracy results of the M193 clones along with the M855 clone results for comparison. 
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All that is necessary for Trolls to flourish, is for good men to do nothing.
In God We Trust. Everyone else needs to post data.
In God We Trust. Everyone else needs to post data.
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Great review!! The only thing that I regret is that you left out the new PMC 855 ammo that is out there.
On another note, is this Federal XM193 different from the American Eagle XM193 you tested? If not, why the different box packaging? Thanks! http://www.cheaperthandirt.com/AMM207-5.html |
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Originally Posted By StealthyBlagga:
Bottom line: all ammo tested is not significantly different. False. There are definitely some statistically significant differences occuring. For example, an upaired, two-tailed t-test comparing the mean radii of the three groups of IMI M855 and AE XM855 produced a p-value of 0.0273. |
All that is necessary for Trolls to flourish, is for good men to do nothing.
In God We Trust. Everyone else needs to post data.
In God We Trust. Everyone else needs to post data.
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Originally Posted By Molon:
Originally Posted By StealthyBlagga:
Bottom line: all ammo tested is not significantly different. False. There are definitely some statistically significant differences occuring. For example, an upaired, two-tailed t-test comparing the mean radii of the three groups of IMI M855 and AE XM855 produced a p-value of 0.0273. I'd definitely side with Molon on this. Just look at the chart- you have an ES ranging from 2.41 to 3.96" at 100 yards. That is absolutely perceptible even without a ruler... The next bulk-brass ammo I buy will be IMI. |
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Originally Posted By Molon:
Originally Posted By ColtGuy42:
Excellent Molon, But Shouldnt the M855 get better Results out of a 1/7 Twist barrel? No. @CG42, if you read about the development of the SS109 projectile, you'll find that a 1/9" twist is the OPTIMAL rate of twist for this bullet, the only reason most 5.56 NATO military weapons have 1/7" twist bbl's is because they want to be able to use the M856 tracer round, which has a ridiculously long projectile for which a 1/6" twist is optimal, and so a 1/7" twist is used as a compromise between the two so that both M855/SS109, and M856 ammo can be used without horrible results. Not horrible, but not ideal either, this twist rate compromise obviously means a little less velocity with M855, and a little less accuracy with M856. 
So there's the long answer for you. |
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Originally Posted By Zhukov:
Marked as "do not archive". Have you updated your collected posts with this yet?  Done! |
All that is necessary for Trolls to flourish, is for good men to do nothing.
In God We Trust. Everyone else needs to post data.
In God We Trust. Everyone else needs to post data.
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Originally Posted By Army_of_One:
I bet if Molon received some ammo in the mail he'd test it for you.  I don't think Molon accepts ammo from others for his tests. It might suggest bias. I hope you will test some plain Lake City 855 to add to the list. Thanks for all your work Molon. |
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Originally Posted By Molon: Originally Posted By StealthyBlagga: Bottom line: all ammo tested is not significantly different. False. There are definitely some statistically significant differences occuring. For example, an upaired, two-tailed t-test comparing the mean radii of the three groups of IMI M855 and AE XM855 produced a p-value of 0.0273. Dude - I think I love you.  What confidence interval?  |
Daddy loves you. Now go away.
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Originally Posted By Molon:
Attack of the (M193) Clones, Part Two: M855 Comparison. This thread is dedicated to Zhukov, for his tireless efforts in reducing the signal to noise ratio in these technical forums. A persnickety comment: don't you mean increasing given that Zhukov (and you, for that matter) are reducing the noise (i.e., denominator) thereby increasing the ratio? In any event, I appreciate the time you take to publish quantitative results in an experimental setting. You're probably one of the last of its kind on this site. |
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Originally Posted By cmcflex:
A persnickety comment: don't you mean increasing given that Zhukov (and you, for that matter) are reducing the noise (i.e., denominator) thereby increasing the ratio? I stand corrected! |
All that is necessary for Trolls to flourish, is for good men to do nothing.
In God We Trust. Everyone else needs to post data.
In God We Trust. Everyone else needs to post data.
|
Originally Posted By Zhukov:
Originally Posted By Molon:
Originally Posted By StealthyBlagga:
Bottom line: all ammo tested is not significantly different. False. There are definitely some statistically significant differences occuring. For example, an upaired, two-tailed t-test comparing the mean radii of the three groups of IMI M855 and AE XM855 produced a p-value of 0.0273. Dude - I think I love you.
What confidence interval?
The confidence interval can be determined from the p value itself. |
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The most curious datum I picked up from your tests was that while Prvi's M855 has the lowest SD, it also seems to have the largest mean radius and largest extreme spread. I'm gathering from this that they are extremely careful at very consistently loading not very consistent bullets...
Otherwise, thanks for the second part of the investigation. I'm looking forward to seeing how various people try to explain what a "two-tailed t test" is... I'm warming up the popcorn popper and planning on sitting back to watch! |
"--you can't conquer a free man; the most you can do is kill him."
Heinlein
Heinlein
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Originally Posted By GHPorter:
The most curious datum I picked up from your tests was that while Prvi's M855 has the lowest SD, it also seems to have the largest mean radius and largest extreme spread. I'm gathering from this that they are extremely careful at very consistently loading not very consistent bullets... Otherwise, thanks for the second part of the investigation. I'm looking forward to seeing how various people try to explain what a "two-tailed t test" is... I'm warming up the popcorn popper and planning on sitting back to watch! That is what I would take away from it as well. The notion of putting two cores inside of a jacket probably leads to some real issues with consistency and tolerances. IMI has had a pretty good rap when it comes to their SS109 bullets for some years now. I would like to see cross sections of all 4 bullets compared against one another. |
| IMI 855 through my 18" 1/8 SPRish upper is the most accurate combo I have, I'm talking about 300yds accurate. It is my most coveted ammo that I have and I have never been able to even come close to replicating it with many 100s of various handloads. |
Zarthan #148
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Originally Posted By Blain:
Great review!! The only thing that I regret is that you left out the new PMC 855 ammo that is out there. On another note, is this Federal XM193 different from the American Eagle XM193 you tested? If not, why the different box packaging? Thanks! http://www.cheaperthandirt.com/AMM207-5.html Great job buddy, what you did (and do) here is great and very appreciated. It would be wonderful if you could test the PMC Xtac along with it's competitors as well...Thanks....<><....:) |
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This is very interesting, especially the groupings at 100yds; I've gotten terrible groups with all the American Eagle M855 I've shot out of both my 20" and 16" 1:9 barrels. So bad that I can't group and zero with it at 25yds! My 69gr SMK handloads shoot great out of both barrels on the otherhand...
Shoots just fine out of the Army's 1:7 guns when I have to qualify however... |
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I'll revive this by saying that I, too, would like to see comparative balistics testing with PMC's "X-TAC" M855 clone. Then, if you have time, a comparison of barrier penetration (vs. the other M855 clones) would rock! 1/2 of my order:  |
"On day's like today, I thank God for the NRA." -me
Team Ranstad 4/1/13
Why can't you admit to yourself that PURE ENJOYMENT is a perfectly valid reason to go shooting?
Team Ranstad 4/1/13
Why can't you admit to yourself that PURE ENJOYMENT is a perfectly valid reason to go shooting?
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I'd also like to see a rigorous objective controlled test of the current Federal Lake City offering of M855. It seems to be much better than in previous years. I have been getting surprisingly tight groups from that ammo in a 1:9 twist carbine barrel.
I think that now that the push is on for the replacement, M855A1, the Lake City plant may be working with closer tolerances on its regular M855. At least that is what seems to be the case. Other tests have also shown than an Australian loading of M855/SS109 is right at 1.1-1.2 MOA. |
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This M855 comparison has PMC X-TAC along with other different M855 variants (velocity highlighted). Velocities measured using an Oehler Model 35P positioned 15 feet from the muzzle out of an16" AR, averaged for 10 rounds per load.
http://www.shootingillustrated.com/index.php/26153/green-tip-accuracy-test/ M855 / XM855 / SS109 “Green Tip” Ammunition Comparison Load Muzzle Velocity (fps) Standard Deviation (fps) Smallest Group (inches) Largest Group (inches) Group Average (inches) Sellier & Bellot SS109 3,006 10 0.57 1.8 1.1 PMC X-Tac Green Tip-LAP 2,899 17 1 1.4 1.1 Prvi Partisan M855 2,944 24 1.2 1.7 1.4 Olympic SS109 2,993 24 0.7 2 1.4 Lake City Arsenal M855 (’11 headstamp) 2,978 25 1.4 2.8 2 American Eagle/Lake City XM855 (’11 headstamp) 2,951 28 1.6 3.2 2.1 Double Tap Ammunition SS109 2,871 28 1.7 3.6 2.6 Winchester M855 2,990 27 2.9 4.4 3.7 |
Put down the Optic! Learn how to shoot the REAL way!
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https://www.youtube.com/watch?v=ligUEAJH25E
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https://www.youtube.com/watch?v=ligUEAJH25E
Attack of the (M193) Clones, Part Two: M855 Comparison. (Page 1 of 2)
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