“MATCH GRADE”


Unlike caliber .30 and caliber 7.62mm ammunition, there has never been a National Match standard for caliber 5.56mm/223 Remington ammunition.

In 1965, the caliber 7.62mm Match ammunition was standardized as M118. The 1965 lot of 7.62mm M118 National Match ammunition had an acceptance testing mean radius of 1.9” for 10-shot groups fired at 600 yards. At that time, this was the smallest acceptance mean radius ever achieved for National Match ammunition since records were kept, starting in the year 1919. Naturally, the ammunition was tested from machine-rested, bolt-actioned, heavy test barrels.

The composite target pictured below shows the twenty-seven, 10-shot acceptance groups (that’s 270 rounds!) of the 1965, M118 National Match ammunition fired from the test barrels at 600 yards. The small circle has a diameter of 6” and the large circle has a diameter of 12”.




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From American Rifleman, September 1965




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From American Rifleman, August 1962





Everything else being equal, (which of course, it seldom is) a mean radius of 1.9” at 600 yards would have a mathematical equivalent of 0.32” at 100 yards. Now, 100 yards is not 600 yards, but then, a semi-automatic AR-15 is not a machine-rested, bolt-actioned, heavy test barrel either. For those reasons, I like to use the mean radius of 0.32” for three 10-shot groups fired in a row (30-shot composite group) at 100 yards as the benchmark for 5.56mm/223 Remington match-grade ammunition, when fired from a semi-automatic AR-15, but that's just the threshold.  My Sierra 55 grain BlitzKing hand-load has produced 10-shot groups with a mean radius "in the ones," 0.1XX" at 100 yards.

The pic below demonstrates jut how far the AR-15 and its ammunition have come since their introduction.  On the left side of the pic is a 30-shot composite group obtained from over-laying three 10-shot groups that were fired in a row off my bench-rest set-up from an AR-15 with a free-floated 20” Colt M16A1 barrel (chrome-lined, 5.56mm chamber, 1:12” twist) using IMI M193 ammunition.  The 30-shot composite group has a mean radius of 1.09”.

The 30-shot composite group pictured on the right was obtained from over-laying three 10-shot groups that were fired in a row off my bench-rest set-up from an AR-15 with a free-floated 20” Lothar-Walther barrel (stainless steel, 223 Wylde chamber, 1:8” twist) using factory loaded Barnes Precision Match 5.56mm 85 grain OTM ammunition (magazine length).  That 30-shot composite group has a mean radius of 0.22”.
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Great info, Molon. I did not know that there was not a match standard for 5.56mm.

Amazing.... that small of a group fired from an AR15 shows how "good" the AR has become.
Molon, you must have quite the steady hand !!  ( I take it you don't drink coffee before accuracy testing.. Lol )

Without trying to detract from the 5.56 aspect of the thread... I wonder what modern .30 cal Match ammo would be capable of in the "machine-rested, bolt-actioned, heavy test barrels."

Actually, I don't remember, what are the accuracy requirements for Mk262 ?

And I'm curious... it looks like the US Army Marksmenship Unit, still uses those similar barrel rests...

molon, your 1x12 twist barrel shoots 193 pretty darn well, better than most.

i know there's been alot of talk about twist rate and 55gr bullets but has it ever been an prove. that 1in7 is too fast for 55gr?  

is there any fact in the statement that some bullets need more distance to "settle down"

That's pretty dam impressive info of what  millspec "match" ammo is capable of. A good percentage of those M118 hits were under .75 MOA at 600 yds. Goes to show it's 10% ammo vs 90% shooter when it comes to identifying the root cause of poor accuracy... LOL

55 Grain FMJ Ammunition Fired From AR-15s With 1:9” and 1:7” Twist Barrels


The Internet Commando:  "55 grain FMJ bullets are over-stabilized and inaccurate when fired from an AR-15 with a 1:7” twist barrel."




Statements such as the one above always seem to be proclaimed by the Internet Commando, without posting any valid, statistically significant data to support that these effects occur, or that if they do occur, that they do so to any degree that has any significant effect on the accuracy/precision spectrum involved with AR-15s firing M193-type ammunition out to distances of 100 yards.

By definition, an “unstable” bullet will have a gyroscopic stability factor of less than 1.0 at the muzzle.  A typical 55 grain FMJ bullet loaded in M193-type ammunition will have a gyroscopic stability factor of approximately 4.27 when fired from a 20” barrel with a 1:7” twist.

[CaptainObvious] 4.27 is not less than 1.0. [/CaptainObvious]


The following demonstration compares the results of firing four, 10-shot groups of the same lot of 55 grain Prvi Partizan M193 ammunition from two different AR-15 barrels; one barrel with a 1:9” twist, the other barrel with a 1:7” twist.  When chronographed from a 20” Colt M16A2 barrel, the muzzle velocity of this lot of PPU M193 was 3219 FPS with a standard deviation of 35 FPS.

The accuracy specification for M193 cited in MIL-C-9963F is as follows:
The average of the mean radii of all targets of the sample cartridges, fired at 200 yards, shall not exceed 2.0 inches.
These averages are from 10-shot groups fired from machine rested, bolt-actioned test barrels.  All things being equal (which of course they seldom are) this specification equates to a mean radius of 1 inch at 100 yards.



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The first barrel used in testing was a 16” Colt HBAR with chrome-lining, a NATO chamber and a 1:9” twist.  This is the barrel found on the Colt 6721.  All of my free-floated Colt 6721 barrels have turned in sub-MOA 10-shot groups at 100 yards when using match-grade hand-loads.

The second barrel used in testing was a 20” Colt HBAR, also with chrome-lining, a NATO chamber and of course a 1:7” twist.  I've owned three of these barrels and they have all turned in 10-shot groups at 100 yards that hover just above one MOA when free-floated and shooting match grade handloads.  I purposely selected the shorter barrel with a 1:9" twist and the longer barrel with the 1:7" twist in order to exacerbate any possible statistically significant influence that the differing twist rates and intendent muzzle velocities might have on the precision of M193-type ammunition when fired at a distance of 100 yards.


Colt 16” HBAR

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Colt 20” HBAR

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Accuracy (technically, precision) testing was conducted from a distance of 100 yards following my usual protocol. The barrels were free-floated during testing.  The fore-ends of the weapons rested in a Sinclair Windage Benchrest and the butt-stock rode in a Protektor rear-bag. Sighting was accomplished via a Leupold VARI-X III set at 25X magnification and adjusted to be parallax-free at 100 yards. A mirage shade was used. The wind conditions on the range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.



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The Wind Probe . . .

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Four 10-shot groups of the PPU M193 were fired from the 1:9” twist barrel. Those groups were over-layed on each other using RSI Shooting Lab to form a 40-shot composite group. The mean radius of that composite group was 1.08”.
As with the 1:9” twist, four 10-shot groups were fired from the 1:7” twist barrel.  Those groups were also over-layed on each other to form a 40-shot composite group; the results were nearly identical to those obtained from the 1:9” twist barrel.  The  composite group had a mean radius of 1.01”. The two composite groups are shown side by side for comparison.



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The entire test as described above was also conducted using a second 16" chrome-lined, NATO chambered Colt HBAR with a 1:9" twist and a second 20" chrome-lined, NATO chambered Colt HBAR with a 1:7" twist.  The ammunition used in this test was all from the same lot of Wolf 55 grain FMJ "Performance Ammunition."  

As before, four 10-shot groups fired from each barrel at 100 yards were over-layed on each other using RSI Shooting Lab and just as before, the mean radii for these 40-shot composite groups showed no statistically significant difference.



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Quality, modern lightweight bullets of copper-jacket/lead-core construction can shoot superbly from AR-15s with fast twist barrels. Typical 55 grain FMJ bullets found in M193-type ammunition do not fall into the quality category.

The 10-shot group pictured below was fired at a distance of 100 yards using 55 grain Sierra BlitzKings from one of my Krieger barreled AR-15s.  The barrel has a 1:7.7” twist.  The group has an extreme spread of 0.448".


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Bryan Litz has offered to pay the plane-fare for anyone willing to travel to his shooting range and prove that to be true.  So far, no one has taken him up on his offer.


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I misread that at first as Brian Litz would pay for my air fare so he could prove something to me.  Hey I like learning. I'd make a good student.

i always took the 'settle down' thing to be this:












 

Very good example. The top graph makes a lot of sense.

I get the idea of the bullet wobbling slightly around its axis. But what most shooters mean when they say "settle down" is that the bullet is printing smaller groups at longer ranges vs a short range.

Gotta love that Oehler set-up too!

Anytime you see "National Match" used in reference to 5.56mm/223 Remington AR-15 barrels be wary as there is no National Match standard for that either.



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Yup.

Got it.

I still love your posts, years later even.  

Great post.

Interesting to know about National Match standards - where the exist and where they don't.  That's a really good point about what "Match" ammo really is.  It's kind of contextual.

From my observation:
- if the ammo shoots 1 MOA (extreme spread), it's good enough to show up to the National Matches.  You can probably get away with worse - the 10 ring is 2 MOA. .  Better ammo won't likely make much difference for all but a very top level at a National Match 600 yard competitors, who are winning by X-ring counts (which is ~1 MOA, and only used as a tie-breaker).  
-But if you show up at an F-Class 600 yard match with 1 MOA ammo, you are in trouble.  
-And if you show up at a benchrest 100 yard match with 1 MOA ammo, you're screwed.


By the way Molon - holy crap man, I have NEVER been able to shoot that well!  Hat's off.

Smaller MOA at longer range, not (necessarily) smaller absolute group size.

Discussed exhaustively in this archive thread.

The first target pictured below shows a measured 5-shot group that was fired by Bryan Litz at a distance of 100 yards on his “shoot thru” target set-up.  The group has an extreme spread of 2.46 MOA.





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The next target shows the impact at 300 yards of the exact same 5 shots that were fired at the 100 yard target.  The extreme spread for the resulting 5-shot group at 300 yards is 2.49 MOA.





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Impossible.

In order for this to happen the angular dispersion of the bullets would have the increase, then decrease, ie, the path would be bent.

The wobble of the bullet settles down in that the precession of the tip decreases, but any dispersion of the trajectory done by the wobble will not just "go away" because the wobble has stopped...it just will not incur more dispersion.

The absolute best result would be the same angular dispersion (the same MOA at all ranges).

For 5.56mm/223 Remington, it's pretty much just marketing.


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For additional info on the subject matter, see my following posts.


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William C. Davis has reported on tests conducted at Frankford Arsenal on this subject matter also.  Using machine-rested, bolt-actioned, heavy test-barrels, one such test that was conducted on an indoor-range involved firing EIGHTEEN 10-SHOT GROUPS on targets at 100 yards and 300 yards.  The average extreme spread for the groups at 300 yards was 3 times as large as the average extreme spread of the groups at 100 yards.

In another test that was conducted at Aberdeen Proving Ground using .30 caliber match-grade ammunition, thirteen 10-shot groups were fired simultaneously through paper screens at different distances.  The mean radius for the groups at 300 yards was 1.0”.  The mean radius at 600 yards was 2.1”.



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Which is pretty much what the testing at Aberdeen Proving Ground and Frankford Arsenal demonstrated that occurs when using statistically significant sample sizes and controlling for environmental factors.



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The only way I see a 100 yard group larger than a longer range one would be by shooter error and a round that is hotter fps than the rest or lower fps than the rest.
Say shooter puts 9 in a ragged hole and shoots a hotter fps round low or a lower fps round high at some point at longer range then it would be possible to get a better moa because of trajectory.
Both would have to happen and in that order or it would be impossible otherwise........Unless crazy wind fluctuations came into play.

There is a bumper sticker that reads sh.. happens.

The requirement calls for a total of ten, 10-shot groups groups to be fired from test barrels at a distance of 300 yards; five 10-shot groups are fired from each of two different test barrels.  The average 10-shot group extreme spread must not exceed 3.5".


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The USAMU requires that their AR-15s are tested with a minimum of three 10-shot groups fired in a row.




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FWIW:

The US Military, at times, refers to the MK262 as either "Special Ball" or "Long Range."
Not quite the Boldly and Brightly marked "National Match" boxes/ammo as previous generations of ammunition......
but you might argue that qualifies as "Match" ammo.........  ???  


https://www.shootingtimes.com/editorial/special-forces-to-civilians-black-hills-mk-262-mod-1-review/99098


2nd FWIW:
In the "Precision Shooting Reloading Guide"  1995     Chapter V    "Reloading the Magnums" starting on page 203...... they discuss this idea of bullets "going to sleep"
......that is comparing groups at say 100yds and smaller groups at say 200yds..............  

They state it is a real but it is clear they are referring to specific loadings........ That is magnum cartridges and not "regular" loadings...............

it used to be pretty common knowledge that a bullet needs some distance to "settle" and that groups would be tighter after that point. it's illustrated well in this graphic



I've always figured that that's why the accuracy specs for military ammo are all at 200m or more, even when it would be much easier to have it be 100m

Mcantu:

I'm not the OP, and it seems as though your comments were replied to 4yrs ago when you first came up with those pictures.  
I have no interest in this thread besides adding the information (the book I quoted) to this.

It seems to me that Molons point here is accuracy and your comments are more based on the affect of bullet instability on terminal ballistics.  

it applies to both the "rounds going to sleep" information you added, as well as instability affecting terminal ballistics at close range

I've heard the arguments back and forth on the theory that bullets settle or go to sleep at different distances, and I'm not a believer.  Bryan Litz, who is the chief ballistician for Berger bullets, doesn't believe it either and cannot find anyone who will prove it exists.

The reason for testing for accuracy at longer distances is so you can see the group dispersion more clearly and reflects velocity variation better.

@Molon

Pics are down. Would you be able to fix them?

Negative. That graphic does not represent that at all. ALL ammunition has a horn shaped accuracy profile, that gets ever wider for MOA group size as distance increases. The bullets never yaw and deviate then get straighter or taper in. Whatever trajectory errors fleet yaw induces are retained throughout the flight paths. The bullet does not sprial around in a corkscrew fashion and then settle in with more parallel flying bullets... it will veer off course and then maintain that trajectory and might get progressively more off course at a slower rate for a bit, but it never groups a SMALLER MOA measurement for average group size. The CHANGE in MOA might slow between 100 and 200 yards vs 25 and 100 yards, but the MOA measurement ONLY gets worse.

Then at ranges increase beyond 400+ yards they start to exponentially get larger, with a large horn flare at extreme distances as the bullet goes subsonic and velocity and wind differences between shots really cause a massive flare.

Anything to the contrary is psychosomatic or random probability that controlled testing will disprove. i.e. there are no guns that shoot 1.2 MOA at 100 yards but .9 MOA at 200 yards. Only shooters that are more careful at 200 yards or luck.

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Done!

https://en.wikipedia.org/wiki/5.56%C3%9745mm_NATO#Mk_262

Wow
much info

There's some laughable stuff in that article pertaining to M855A1.

From the article: "The steel-tip penetrator of the M855A1 is noticeably separated from the jacket of the bullet and can spin, but this is part of the design"

While the penetrator on some of the early lots of M8551 did spin, it was not "by design".   The copper jacket of the bullet is now appears to be "pressed" into the steel penetrator and not one of the more than 100 rounds of M8855A1 from a 2021 lot that I inspected, did the penetrator spin.


"Ballistics for both rounds are similar and do not require weapons to be re-zeroed"

In only one of the barrels that I've tested with M855A1, was the point of impact close to point of impact of M855.  In one barrel, the point of impact for the M855A1 was 2.5 MOA away from the zero of M855.  In a third barrel, the point of impact of the M855A1 was completely off the target when the barrel was zeroed with M855.



"The longer bullet and reverse-drawn jacket make it more stable and accurate in-flight"

The data in Ballistic Performance of Rifle Bullets by Bryan Litz shows the opposite.

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