hand-load accuracy data added


M855A1 Accuracy and Velocity




M855A1 ammunition is manufactured at the Lake City Army Ammunition Plant near Independence, Missouri.  The lot of Lake City M855A1 ammunition that was evaluated for this article was manufactured in January of 2021. There were no malfunctions of any kind for this ammunition in any of the four barrels that were used in this evaluation.

M855A1 is packaged in kraft boxes with 30 rounds in each box.  The rounds are on stripper clips with 10 rounds per clip.





The M855A1 cartridge has a nominal over-all length of 2.250”. This over-all length gives the A1 projectile a jump of 0.132” to the lands of a Colt 5.56mm NATO chamber.

M855A1 is loaded in Lake City brass.  The brass cases have the annealing iris still visible.  The headstamp for this lot reads: ”LC - 21” along with the NATO cross.  The case-head stamp exhibits the octal station identifiers used on Lake City SCAMP machinery.  The primer pocket has four “stab” crimps and a minimal amount of sealant. The case mouth has a generous amount of asphalt sealant and is crimped into a cannelure on the bullet.  












Lake City M855A1 ammunition is charged with the St. Marks Powder SMP-842, which is a flattened ball powder.  Sampled powder charges had an average weight of 26.4 grains.





The M855A1 bullet is considered a 62 grain round, however, sampled bullets had an average weight of 62.6 grains. The M855A1 projectile is constructed from three different components; a solid copper core, an exposed steel penetrator and a reverse-drawn copper jacket that holds the other two components together.  Since this bullet does not have a lead core, the only thing that fragments upon terminal impact is the copper jacket.

It has been reported that with early lots of M855A1, it was possible to “spin” the steel  penetrator inside the copper jacket with your fingers.  This did not occur with any of the current rounds that I sampled.





The M855A1 projectile has a lower specific gravity than conventional lead-core, copper jacketed bullets and is significantly longer than the legacy M855 projectile.  The A1 projectiles that I sampled had a nominal length of 1.00”.
 
According to Ballistic Performance of Rifle Bullets by Bryan Litz the average G1 ballistic coefficient of M855A1 is 0.291 and the average G7 ballistic coefficient is 0.149.  The same reference states that M855A1 has a nominal gyroscopic stability factor of 1.41 when fired from a barrel with a 1:8" twist and 1.85 when fired from a barrel with a 1:7" twist.















Velocity


I chronographed the Lake City M855A1 ammunition from a semi-automatic AR-15 with a chrome-lined, NATO chambered, 20” Colt A4 barrel with a 1:7” twist.




Chronographing was conducted using an Oehler 35-P chronograph with “proof screen” technology. The Oehler 35-P chronograph is actually two chronographs in one package that takes two separate chronograph readings for each shot fired and then utilizes its onboard computer to analyze the data to determine if there is any statistically significant abnormality in the readings. If the readings are suspect, the chronograph “flags” the shot to let you know that the data is invalid. There was no invalid data flagged during this testing.

The velocities stated below are the muzzle velocities as calculated from the instrumental velocities using Oehler’s Ballistic Explorer software program. The strings of fire consisted of 10 rounds over the chronograph.










Each round was single-loaded and cycled into the chamber from a magazine fitted with a single-load follower. The bolt locked-back after each shot allowing the chamber to cool in between each shot. This technique was used to mitigate the possible influence of “chamber-soak” on velocity data. Each new shot was fired in a consistent manner after hitting the bolt release. Atmospheric conditions were monitored and recorded using a Kestrel 4000 Pocket Weather Tracker.






Atmospheric conditions

Temperature: 76 degrees F
Humidity: 47%
Barometric pressure: 30.09 inches of Hg
Elevation: 950 feet above sea level


The muzzle velocity for the 10-shot string of the Lake City M855A1 ammunition fired from the 20” Colt barrel was 3131 FPS with a standard deviation of 18 FPS and a coefficient of variation of 0.59%.

For those of you who might not be familiar with the coefficient of variation (CV), it is the standard deviation, divided by the mean (average) muzzle velocity and then multiplied by 100 and expressed as a percentage. It allows for the comparison of the uniformity of velocity between loads in different velocity spectrums; e.g. 77 grain loads running around 2,650 fps compared to 55 grain loads running around 3,250 fps.

For comparison, the mil-spec for M193 allows for a coefficient of variation of approximately 1.2%, while one of my best 77 grain OTM hand-loads, with a muzzle velocity of 2639 PFS and a standard deviation of 4 FPS, has a coefficient of variation of 0.15%.


I also chronographed the Lake City M855A1 ammunition from three different 14.5” barrels in the same manner as described above for the 20” Colt barrel.  Chronographing of the 14.5” barrels was conducted immediately after the chronographing for the 20” barrel.


A 10-shot string of the Lake City M855A1 fired from a 14.5” Hodge Defense barrel had a muzzle velocity of 2939 FPS with a standard deviation of 23 FPS.





A 10-shot string of the M855A1 fired from a 14.5” Colt M4A1 SOCOM barrel had a muzzle velocity of 2949 FPS with a standard deviation of 17 FPS.  





A 10-shot string of the M855A1 fired from the Bravo Company 14.5" ELW barrel had a muzzle velocity of 2966 FPS with a standard deviation of 19 FPS.





The muzzle velocities for the Lake City M855A1 are summarized in the table below.





For comparison, the next two tables show the muzzle velocities for legacy military 5.56mm ammunition that also uses 62 grain projectiles: M855 and MK318 Mod 0.









Accuracy


I conducted an accuracy (technically, precision) evaluation of the Lake City M855A1 ammunition following my usual protocol. This accuracy evaluation used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any group-reduction techniques (e.g. fliers, target movement, Butterfly Shots).

The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for. Also, a control group was fired from the test-rifle used in the evaluation using match-grade, hand-loaded ammunition; in order to demonstrate the capability of the barrel. Pictures of shot-groups are posted for documentation.

Shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The barrel used in the evaluation was free-floated. The free-float handguard of the rifle rested in a Sinclair Windage Benchrest, while the stock of the rifle rested in a Protektor bunny-ear 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. Wind conditions on the shooting range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.





The Wind Probe.




The test vehicle for this accuracy evaluation was one of my semi-automatic precision AR-15s with a 20” stainless-steel Lothar-Walther barrel. The barrel has a 223 Wylde chamber with a 1:8” twist. Prior to firing the Lake City M855A1, I fired a 10-shot control group using match-grade hand-loads topped with the Sierra 77 grain MatchKing (without a cannelure). That group had an extreme spread of 0.56”.











the control group . .




Three 10-shot groups of the Lake City M855A1 ammunition were fired in a row with the resulting extreme spreads:

1.78”
2.65”
1.78”

for a 10-shot group average extreme spread of 2.07”. The three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for the 30-shot composite group was 0.63”.



The smallest 10-shot group . . .





The 30-shot composite group . . .




M855A1 compared to other mil-spec rounds . . .





In the category of useless trivia, the M855A1 bullet cuts the cleanest holes in paper targets of any 5.56mm/223 Remington ammunition that I’ve ever tested.  It’s like wad-cutters for the AR-15.









I also fired a 10-shot group at 100 yards off of sand-bags from each of the 14.5” barrels that were used in chronographing the M855A1 ammunition.

A 10-shot group fired from the Colt M4A1 SOCOM barrel had an extreme spread of 1.85”.  






A 10-shot group fired from the Bravo Company 14.5" ELW barrel had an extreme spread of 2.15”.





A 10-shot group fired from the 14.5" Hodge Defense barrel had an extreme spread of 2.51".




fired cases

left: from a 5.56 Colt M4A1

right: from a 223 Wylde





Lastly, for any Internet Commandos in our viewing audience today, here’s a pic of a sub ¾ MOA group of the Lake City M855A1 ammunition fired at 100 yards.  The group has an extreme spread of 0.59”.









Part 2

Hand-Loaded M855A1 Accuracy


When M855A1 was introduced, we were told by people with “inside information” that this new load produced “match-like” accuracy, yet none of these people where ever able to show statistically significant data to support this claim.  The test results that I obtained with M855A1 certainly didn’t show “match-like” accuracy.

The Crane Naval Surface Warfare Center has done extensive testing with M855A1 fired from AR-15s mounted in a heavy, sliding machine-rest test fixture. The Crane Naval Surface Warfare Center is involved in developing special munitions and weapons for our warfighters.  They’re not interested in sales hype and propaganda; they’re only interested in facts.  They’re not driven by profit margin; their goal is providing our Special Operating Forces with the best tools for accomplishing their missions.  When it comes to evaluating the accuracy of ammunition Crane uses 10-shot groups.





With newly barreled upper receiver groups mounted in the heavy sliding machine-rest test fixture, M855A1 was only able to produce a 10-shot group average extreme spread of 2.74” at 100 yards with an average mean radius of 0.85”.  With a round count of 3,600 rounds through the barrels, M855A1 was only able to produce 10-shot groups with an average extreme spread of 3.84” at 100 yards with an average mean radius of 1.10”.  

The Lothar Walther barrel that I used to test the M855A1 for this evaluation had approximately 3,350 rounds through it at the beginning of my M855A1 testing and as we saw it produced an average 10-shot group extreme spread of 2.07” at 100 yards.  A 30-shot composite group of the M855A1 from the Lothar Walther barreled AR-15 had a mean radius of 0.63”.

People are often quick to point out that the lack-luster accuracy of legacy M855 manufactured at Lake City is due among other things to the fact that M855 is composed of three different components; the lead core, the steel penetrator and the copper jacket, yet people seem to gloss over the fact that M855A1 is also composed of three different components; the copper core, the exposed steel penetrator and the copper jacket.





We know that the M855A1 that the US Army based their accuracy claims on was not manufactured on the SCAMP machinery at Lake City, but rather the slower BAM machinery. The speed of the SCAMP machinery is significantly faster than the older BAM machinery.

The M855A1 that I evaluated was produced on the SCAMP machinery.  These M855A1 projectiles themselves showed quite a bit of variation.  As an example, the base to ogive measurements were all over the map.
 
The picture below shows two M855A1 bullets that I pulled from the lot of ammunition that I tested.  The bullet on the left shows a properly shaped base. Notice the beveled heel and the flat base.  The bullet on the right has a “ridge” running around the bottom of the bullet and the base is recessed.  Apparently, the speed of the SCAMP machinery comes at a cost.





The US mil-spec for the accuracy/precision of the M4 carbine firing legacy M855 from a machine rest allows for an extreme spread of 5.0” for a 10-shot group at 100 yards.




The US mil-spec for the accuracy/precision of the M4 carbine firing M855A1 from a machine rest allows for an extreme spread of 5.6” for a 10-shot group at 100 yards.



It seems rather odd that the M4 carbine needs to have a larger extreme spread to meet the mil-spec when firing the load that supposedly has “match-like” accuracy.  Most of my accuracy evaluation data for Colt M4 carbines was lost in a tragic boating accident, but I was able to obtain a 1.24 MOA 10-shot group from a Colt M4 barrel using true match-grade hand-loads (albeit, this group was only fired from 50 yards).



Unlike caliber .30 and caliber 7.62mm ammunition, there has never been a National Match accuracy 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”.


From American Rifleman, September 1965


From American Rifleman, August 1962.
Everything else being equal, 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, so 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 threshold for match-grade ammunition in 5.56mm/223 Remington when fired from a semi-automatic AR-15.  A mean radius of 0.32” at 100 yards is equivalent to an average extreme spread of 1.025” for 10-shot groups.

The first step that I took in developing a hand-load using M855A1 bullets was to cull the projectiles with the “ridged” bases.


Next, the bullets were sorted by weight.  A group of the bullets within the mean weight were further sorted by their base to ogive measurements and the bullets within this mean measurement were used for the hand-loads.

The cases used for these hand-loads were virgin Lake City cases that were weight sorted.  The necks of these cases were then chamfered, deburred and neck sized using a bushing neck die. The primer pockets and flash holes were uniformed.  Priming was conducted using a Sinclair hand priming tool.

The cases were charged with powder using an RCBS Match Master powder dispenser and the bullets were seated on a single stage Forster press.  10 rounds of each increment of powder charge weights were used to develop a load at 223 Remington velocities.  Most 5.56 loads can be hand-loaded to shoot more accurately/precisely when down-loaded to 223 Remington velocities.




The hand-loads were fired from my bench-rest set-up using the same Lothar Walther barreled precision AR-15 used to test the factory loaded M855A1 and all my usual procedures were followed.  The smallest 10-shot group produced in this test had an extreme spread of 1.14” and a mean radius of 0.427”(and a score of 100-10X).  Not quite match-grade, but close enough to call it “match-like” I guess.




…..

Good stuff, as always. Thanks for sharing.

Great info and post, thank you.  I think the M855A1 is around the pinnacle of ammo technology / performance in the 5.56 caliber cartridge.  A good choice by the US military to adopt it.  

In my experience in testing earlier lots, I got closer to 3,200 FPS from an 18.5" barrel.

Ditto.

Thanks for the post, seems the A1 is a little inaccurate huh?

It's an improvement over legacy M855, but as you can see it certainly doesn't have "match-like" accuracy like the people claiming to have secret squirrel information said that it did.

..

Lieutenant Colonel (retired) Rob Harbison (a member of the 1996 United States Olympic Shooting Team) shot it at Camp Perry in 2012 using a USAMU National Match M16 with iron sights.  

M855A1 at Camp Perry
Army's newest general purpose round shows accuracy in rifle competition
By Eric Kowal, RDECOM, army.mil
August 29, 2012

Army's newest general purpose round shows accuracy in rifle competition



PICATINNY ARSENAL, N.J. (Aug. 28, 2012) -- The Army's new M855A1 Enhanced Performance Round is performing well under combat conditions in Afghanistan, but how does it stack up in rifle competition?

The Army recently put it to the test against some of the best marksmen in the world at the 2012 National Rifle Association's National High-Power Rifle Championships at Camp Perry, Ohio, in early August.

The Army's newest 5.56mm ammunition was initially fielded to troops in Afghanistan in July 2010 as a replacement for M855 "green tip" ammo. As green tip ammo stockpiles are drawn down Soldiers will begin using the new M855A1 Enhanced Performance Round, or EPR, for training as well as combat.

Rob Harbison, a contractor supporting small caliber ammunition capability development at Fort Benning, Georgia, competed in the matches at Camp Perry firing the EPR. This was a special event for the Project Manager for Maneuver Ammunition Systems and the Army's Maneuver Center of Excellence as it was an opportunity to showcase the capabilities of this new round.

"We felt we had an excellent opportunity in Rob to put the M855A1 EPR in the hands of a Camp Perry national competition veteran," explained Lieutenant Colonel Philip Clark, the Army Product Manager for Small Caliber Ammunition. "We had every confidence that his abilities, coupled with what we know to be quality ammunition, would yield positive results."

An act of Congress established the National Shooting Matches in 1903 to promote rifle practice and firearms safety. The matches are open to military and civilian competitors, and have been hosted by Camp Perry, a National Guard training center in Ohio, since 1907.

The matches are co-administered by the Civilian Marksmanship Program, or CMP, and the National Rifle Association. The National Matches are the premier shooting competition in the United States and draw the best competitive marksmen in the country.

The competition began July 30 with the CMP's President's Rifle Match. The President's Rifle Match is a 30-shot match fired in one day. Competitors fire M16-series or M14 series (and civilian equivalent) weapons at 200, 300, and 600 yards at bull's-eye targets.

The top 100 competitors are considered to be in "The President's Hundred" for that year.




Harbison placed 169 out of 1,242 of the world's finest marksmanship competitors on that day, putting him in the top 15 percent.

The competition would then pick back up August 5-10, with the NRA National High Power Rifle Championships. This is a much less restrictive competition which allows the use of "unlimited" rifles with modified sights, custom stocks, high performance calibers and other ergonomic improvements over standard issue military service rifles.

Harbison finished 86th of 385 competitors, and 46th (17th civilian) of 200 marksmen competing with an M16-type rifle.

Throughout the competition Harbison had several noteworthy performances, including firing a perfect 200 points in the Coast Guard Trophy Match, 20 shots fired from the sitting position at 200 yards. He finished 17th overall in that match (of 385 competitors) in the top five percent.



Harbison scored a perfect 100 on the final string of ten shots during the Air Force Cup Trophy Match, fired at 600 yards from the prone position. That is 10 shots in a row within the 12-inch, 10-point ring at 600 yards with combat ammunition.

While at Camp Perry, Harbison discussed the new round with his fellow competitors and answered questions about the ammunition.

Harbison was happy with the performance of the EPR with his scores showing the Army's newest general purpose round is accurate enough to go toe-to-toe with the best ammo that can be bought or hand-loaded.

"Using the Army's newest general purpose ammo was not a hindrance," Harbison said. "When I did my part, M855A1 was right on target all week."

"I don't think I could have scored any higher if I was using match grade competition ammunition," Harbison added.

COMPARISON TO M855

The EPR contains an environmentally-friendly projectile that eliminates up to 2,000 tons of lead from the manufacturing process each year in direct support of Army commitment to environmental stewardship. This is a clear example of how "greening" a previously hazardous material can also provide extremely beneficial performance improvements.

There are three main areas in which the new round excels: soft-target consistency, hard-target penetration, and the extended range at which it maintains these performance improvements.

According to Army officials, M855A1 represents the most significant performance leap in small-arms ammunition in decades.

Sinister:
Thanks for posting that..........  interesting article.

I'll be honest, me personally, feel it's a well done sales pitch.
Though it does seem to confirm Molons evaluation of it.

And having shot alot at Perry and with various M855/A1 in competition........ I'd respectfully disagree with his statement:

"...."I don't think I could have scored any higher if I was using match grade competition ammunition," Harbison added........."

That honestly, is a bold mis-statement.
He clearly had good zeros, good conditions and is a good shooter.
He would have placed much higher with better ammunition.  

I tested 110 rounds of m855a1 and averaged 3.55moa, I believe. 10 shot groups. The velocity was boringly consistant. Due to the accuracy through a weapon that put browntip into 1.5-1.75moa groups and even XM556FBIT3 into 2-2.5moa groups and mk318 into 2.0moa groups, I discontinued the use of m855a1. I noted no abnormal function or wear marks from the limited testing done. The barrel had roughly 8500 rounds, including 2000 rounds of bimetal jacket ammo through it at this point. No degradation had been noted with other rounds of established baseline.

Great info! Thanks for posting!

There's no rabbit-ass way I'm shooting M855A1 in place of true match ammo at Camp Perry -- I agree that's just insane.

Conditions must have been a gift from God to perform like that at 600 yards.

My experience coaching new and intermediate shooters pointing rack-grade M4A1s with ACOGs to 500 yards is M855A1 holds E-type silhouette well at 400 yards if the winds are favorable, but you really have to work hard at 500.

LMAO! ............
It's funny you mention that......... in a match not too long ago, I started with the same set up at 600yds........and well, it was interesting!  And yes, same experience....... 400 and in......... good.

Not calling the Man a liar and he's a good shooter.  But there are three parts to this:  shooter, rifle and ammo.  And that ammo (M855A1) has some clear limits like any other, which you cant get around.  You can't hope or pray for a better BC for example.  Or as Molon, points out.........when you need to make several million rds a year, quality will suffer.  You can't get around that.      

He was trying to sell some ammo and he did a good job.

BTW...........Wasn't Dennis DeMilles claim to fame that as a Marine shooter- rack grade M16, M855, and Marine equipment- that he set numerous records in their Military matches?
IE cleaned the 200yd standing?
Sometimes the Shooter is pretty good.

On the flip side, he did better with (technically ) ball ammo than the 78% he beat, who most likely all had match ammo. If there are doubts to the story, I'm sure there are records of the matches right?


ETA: I should have watched the video first. I shows the actual match and some of the hits

M855A1 is not "technically ball ammo". It has a reverse drawn jacket.

Nobody is doubting that he used M855A1 in the match.  What people do doubt is whether he used M855A1 that was manufactured on the SCAMP machinery as it currently is, or, did he use M855A1 that was manufactured on the BAM machinery with cherry picked components and a cherry picked final lot.

The US mil-spec for the accuracy/precision of a machine-rested M4 firing legacy M855, allows for an extreme spread of 5.0” for a 10-shot group at 100 yards, yet the US mil-spec for the accuracy/precision of a machine-rested M4 firing M855A1, allows for an extreme spread of 5.6” for a 10-shot group at 100 yards.

If M855A1 manufactured on the SCAMP machinery produces "match-like" accuracy, why did the Army have to increase the allowable extreme spread for it compared to legacy M855?



....

I realize that. I wasn't sure what to call it so I just went with what is on the tin

I shot a 192-5X at 500Y, on the Army NMC Course with a rack-grade FN M4A1, shooting M855A1 straight out of the bandolier, during the 2021 US Army Small Arms Championships.

I shot it slick, no shooting jacket, no sling, with the magazine on the ground.

M855A1 is capable of high levels of precision.

Would I shoot it at Camp Perry?  Uhhhh......No.

Dennis is a great guy and accomplished shooter.

I'm not sure what targets the Marines shoot during their division matches (bullseye or silhouette) -- but there's a HUGE difference between the two.

Case in point -- you don't have to hit in the black to score on their silhouette targets (200 and 300 yards on the short target, 500 on the taller):

Attached File


The Marine bullseye target is a whole lot less forgiving:



I personally think one of M855A1's limits is velocity decay at 500 yards and further -- the slower it flies the more I suspect it's affected by wind.  A1 projos weigh 62 grains apiece and are roughly the same length as Sierra 77s.

Attached File

I'm not questioning the story and yes you could look at the records on the CMP site for the P100 he shot in.
But I don't need to.

He was there to "sell" a product and did a nice job doing it.  He shot well.  

Otherwise, he was -roughly- getting 2MOA groups- from his description- which is what I've found and Molon did as well.  Using good equipment.

But otherwise, (Again since he seems to be a very good shooter and had a good rifle), he probably would have scored much higher with better ammunition.

M855A1 ammunition is good but it cannot compare to "match ammunition"............. because:
-it isn't as accurate, meaning group size.  (at distance that will mess with zeros)
-the BC is quite low compared to say the 77gr SMK, but really any of the "match" bullets.  (the wind will chew you up).
-it's a mass produced bullet, so the consistency isn't there.   (you will get fliers that mean lost points).

BTW........ if you don't know it, the P100 match is open to all and so you have everyone from literally first time shooters to nationally ranked champions.

I don't know the exact details of his Wins, to be honest.  I brought it up to illustrate that good shooters can do good work with medicore ammunition.  

Yes to the underlined comment......... no doubt.  
BTW if the published BC's are accurate the M855A1 has the same as the Hornady 53gr VMAX.  Going leadfree means a lllllooonnngg bullet.  
That last match I referenced earlier, there was some wind.  At 5-600, I was fighting it, it was chewing me up. (And usually with my "regular" SR set up, i'm usually mid 190's at 600).

Seems the people in this thread mentioning using it over 400 were using an M4 while the Camp Perry guy was shooting it out of a 20" barrel. Maybe that helped some with the wind?

both FN and Colt "SOCOM" profile barrels WAY outshoot 20" barreled M16A4's.  I have printed several 1.5MOA 10rd groups at 300Y with an M4A1/M855A1, in competition.

ETA:  NGMTC Schoolhouse uses .292 as the BC for M855A1

Good info. I was thinking more of the velocity difference of 14.5" vs 20" at over 400 yds

My chrono data for 855A1 -

59*f
4227' ASL
29.94 BARO
Humidity....Idunno...i'm in Idaho, so not a lot...

14.5 Colt SOCOM Barrel - 2975fps
20" FN GOVT Profile M16A4 - 3124fps
(ETA - Pretty close to what MOLON came up with....and he's way better at this than I am)

Maybe, but this stuff is Gold, too.

My kid shot his M4 w/ACOG in a lot of Guard competitions at higher altitude in New Mexico, Wyoming, Utah, and Colorado.  I'm fairly sure the density altitude had the bullets flying close to how they would out of a 20-incher at lower altitude ranges (Texas, Georgia, Alabama, Arkansas, North Carolina, Virginia, Tennessee, Indiana, and Ohio).

I had to dial up a minute when I shot at Benning or CP. Robinson

Several comments:

@cvtrpr.................. Yes, the listed G1 for the .224 53gr VMAX by Hornday is 0.290.  You are saying 0.292 and Litz is quoted as saying 0.291.  
OK, not EXACTLY..... but I'd say the same for practical purposes.  

FWIW:  from shooting on Colorado 5-7000ft, then at Camp Perry (574ft), I too am coming up around 1 MOA at 600.  

@mcantu........ Im out of town so I don't have all my notes with me but using cvt's info for example, I doubt the added velocity would help much at all.
As reflected by the -relatively- low BC of the bullet, it's shedding velocity pretty quickly.

 

I'm amazed.  (Thanks for the post btw - another solid).  I would never have thought a mass produced GI 3 component bullet would shoot that well.  The accuracy QC of the 3 component M855 was so mediocrity. I just wouldn't have guess they would up their game this far.

Wow.

TBH, as a tax payer, I have to wonder if the value of GI ball being that precise is really worth it.  But as a shooter - WANT!

Every advantage we can give the battlefield soldier is worth it.  I'm a retired E7, having been an Cavalryman and Infantryman.  Two Iraq campaign stars.  The 855A1 is a fantastic bullet compared to regular 855/SS109.  Wish it was around when I was deployed.

It's an interesting question.  If you were to ask Ukraine right now if they could have twice as many rounds of M193 55 gr ball, or half as many rounds of the better M855A1; I am not so sure they would pick the M855A1.

Valid question.  I believe the M855A1 was developed in response to the Russian Army's "Ratnik" armor system, and was intended specifically to defeat that armor system.  So, I do wonder which they'd choose.

Great eval, Molon!  As always scientifically done and gentlemanly conveyed.

I smile everytime I see one of those overpriced hodge barrels underperform for the claims they make about it

My results are similar to the .mil results. M855 has been notably more accurate.

M855A1 was developed because the State of Massachusetts told the Army to find a substitute for lead or close the Camp Edwards and Fort Devens small arms ranges.

Anyone read John Plaster's 2014 article in the American Rifleman?

When they tested it with 1/7 twist barrels, groups that it produced look familiar to what has been reported here. With 1/9 twist barrels, it produced groups that were half of the size of the 1/7 groups.

No their groups did not "look familiar to what has been reported here."  They were shooting statistically insignificant 5-shot groups and even went so far as to throw out a "flyer" for every group and only count four of the five shots to try to get "match-like" accuracy.

Per the third edition of Ballistic Performance Of Rifle Bullets, the minimum twist required for stability of M855A1 is 1:8.7".

...

Yeah, I'm not arguing the testing methodology he used. I'm not sure he even followed the American Rifleman's technical spec of five, five shot groups.  The use of the term familiar, is simply my way of stating non-match grade.

It would be interesting to see if a 1/9 twist barrel would improve things, since spinning unbalanced bullets too fast contributes to large groups.

As I stated above, a 1:9" twist barrel won't even produce an appropriate gyroscopic stability factor for the M855A1 projectile, and my match-grade Lothar Walther barrel used in my testing has a 1:8" twist.

The M855A1 projectile is longer than a 77 grain Sierra MatchKing and nearly as long as a 70 grain TSX, which key-holes when fired from a 1:9" twist barrel.






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Yeah I was looking at that data sheet and saw the same thing. That's a calculated number, not somthing that was tested. Could be different lots of projectiles or Plaster's barrel was a little faster than 1/9 or maybe it was 100*f when he tested it.

Regardless he reported that his rifle shot smaller groups with a slower twist barrel.

Disclaimer - this is "tribal hearsay" knowledge - The NGMTC gunsmith, Mike Hester, told me that the reason they inspect barrels at check-in at the WPW Matches is to ensure there are no 1:9 twist barrels, which would provide an unfair advantage against the normal 1:7 rack-grade arms room guns.

When I went to AASAM in the early 90s there was some chatter among team members about F-88s with 1/9 twist barrels vs. our A2s with 1/7 twist barrels. All the ammo issued was ADI 62gr ball, which was quite accurate and they were shooting very well with it.

Were those 1:9" twist barrels chrome-lined, NATO chambered barrels?


An Accuracy Comparison of M855 When Fired From 1:9” Twist and 1:7” Twist Barrels.

This test will compare the accuracy (technically, precision) of M855, produced by Israel Military Industries (IMI), when fired from an AR-15 with a 1:9” twist barrel and an AR-15 with a 1:7” twist barrel. The IMI M855 is the singularly most accurate and consistent loading of all the M855 clones that I have tested to date.


IMI M855 is loaded with a 62 grain FMJ bullet with a cannelure. It also has a steel penetrator seated in the ogive portion of the projectile. This makes the projectile unusually long for its weight, as well as giving it a lower specific gravity. The ammunition is charged with "ball powder". The primers are sealed and crimped in placed. The bullet is also crimped in place and the case mouth is sealed with an asphalt sealant.


Chronograph data for the IMI M855 was obtained using an Oehler 35P with "proof screen" technology. All velocities listed are muzzle velocities as calculated from instrumental velocities using Oehler's Ballistic Explorer software program. All strings of fire consisted of 10 shots each.





This accuracy evaluation used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any Group Reduction Techniques (e.g. fliers, target movement, Butterfly Shots).

The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for. Also, control-groups were fired from the barrels used in the evaluation using match-grade, hand-loaded ammunition; in order to demonstrate the capability of the barrels.

All shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The barrels used in the evaluation were free-floated. The free-float handguard of the rifle rested in a Sinclair Windage Benchrest with the aid of a Sinclair fore-arm adaptor, while the stock of the rifle rested in a Protektor bunny-ear 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. Wind conditions on the shooting range were continuously monitored using a Wind Probe. All rounds were fired from the magazine. Each upper was fired using the same lower. The set-up was very similar to that pictured below.

The barrels used in this evaluation were both Colt HBARs with NATO chambers and chrome lining. The 1:7” twist barrel was 20” in length and the 1:9” twist barrel was 16” in length. When fired from the 16” barrel with a 1:9” twist, the M855 projectile will have a gyroscopic-stability-factor of approximately 1.24 and when fired from the 20” barrel with a 1:7” twist the gyroscopic-stability-factor will be approximately 2.07.

Prior to the firing of the M855, control groups were fired from the test barrels using match-grade handloads seated with Sierra 55 grain BlitzKings. The 10-shot control group fired from the 1:7” twist barrel had an extreme spread of 1.17” and the 10-shot control group fired from the 1:9” twist barrel had an extreme spread of 0.89”.


Three 10-shot groups were fired from the upper with the 1:9” twist barrel in the manner described above. The extreme spreads for those groups measured:

2.72”

2.19”

2.24”

for a 10-shot group average of 2.38”. The three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for the composite group was 0.76”.

In the same manner as above, three 10-shot groups were fired from the upper with the 1:7” twist barrel. The extreme spreads of those groups measured:

2.14”

3.01”

1.71”

for a 10-shot group average of 2.29”. As before, the three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for this composite group was 0.68”.


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And yet, he didn't provide any actual data to support that claim.  No information on what actual 1:9" twist barrel he used. No actual information on what manner the groups from the 1:9" barrel groups were fired. No group size data, no number of shots in those groups data, no documentation of the targets.

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Molon, as always YOU ROCK!
Thanks again for all you do for us

I did a 1:9 vs 1:7 barrel comparison with my AUG. Nothing definitive but with 69gr and 77gr match ammo, the 1:9 barrel always shot tighter groups. Both barrels are CHF, chrome lined. The 20" barrel is 1:9 made in Austria and the 16" is 1:7 made by FN in the US

https://www.ar15.com/forums/Armory/AUG-Barrel-Comparison-1-9-Austrian-20-vs-1-7-FN-16/43-522944/

I only had 50 rounds of each so that's why there were not equal number of groups

I did get to shoot their rifles a few times and they were pretty accurate, but it was 30 years ago. I think the Austrians adopted the AUG in 1977, and I'm not sure if there was a NATO chamber at that time. NATO was working on a new and improved 5.56 ball cartridge which got type classified as M855 in the early 80s, but Austria is not in NATO. They probably had a good idea that they were going to produce adopt a cartridge with a longer bullet, so decided on a 1/9. The French however went with a 1/12 in the same time frame.

I'm also not sure if the barrels they had were original Austrian AUG barrels, which were 1/9 or ADI barrels. Just a little internet sleuthing seemed to provide mixed results with regard to twist rate on those original F-88 barrels, but I think they must have been 1/7. I do remember the scuttlebut about the 9 twist barrels though.

I wish I had saved some targets fired from my Steyr USR from years ago.  The USR had a different barrel than the AUG and was reported to be manufactured by ADI.  The USR barrel was the best machined chrome-lined barrel I had ever seen.  The lands almost looked as if the barrel was cut-rifled and the chrome-lining was incredibly uniform.  That USR was the most accurate "AUG" I had ever fired.

Does anyone know if M855A1 is actually available for purchase?

I ran into this link a few days ago.  Web site was created in September 2022.  Is this a scam or have any of you actually received M855A1 ammo from this company??

https://nfadefence.com/product/m855a1/

I apologize if posting a link is not permitted.    

company name is nfdefense.

Some swag from 30+ years ago. The AMP (Applied Marksmanship Practice) was 240, 260 & 280. If I remember correctly I was pretty close to getting a 280, but that only counts in nuclear war and hand grenades.

Only payment options for that site seem to be Venmo, Zelle and bitcoin.  That's usually a good indicator that it's a scam.

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De nada.

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