Army vs. Marine Rifle Round or What Some Would Like You to Believe…

Posted on: July 9th, 2015 by Will Rodriguez 21 Comments
M855A1 (L), Mk 318 (R)

The House Armed Services Committee asked the Pentagon in late April why the Army and the Marines use different primary ammunition types in their most common small arms caliber 5.56mm.  It’s a curious contradiction since the Army and Marines are fighting the same enemy in the same regions of the world.  Now that the worldwide operational tempo has slackened a tad, it makes sense to look for some significant cost savings and simplification of supply to be realized by going to a common munition.  The Secretary of Defense has until March next year to explain meanwhile, testing is ongoing.

This question by Congress caused a virtual avalanche of commentary in the blogosphere with an overwhelming majority of it slanted to the Marine Corps benefit assuming it made a better choice and trying to create a fight between branches where none is necessary.  Let’s try and get past the BFF branch perspective and come to understand how the current situation arose and objectively assess the two rounds.


For most of the last three decades the Army and Marines primary 5.56 round has been M855 or “green tip” such named because of its green painted tip to differentiate it from other ammunition.  M855 was originally created for the M249 SAW by our European allies and is called SS109.  It was type classified as M855 for US use in the M16A2 rifle in the mid-80’s.  M855/SS109 was developed in the 1970’s with the desire to create a round that would penetrate body armor and helmets typically equipping Soviet forces of the period.

M855’s armor penetration is provided by a small steel penetrator placed in the bullet during production.   Yaw provided M855’s anti-personnel effect.  Yaw is the tendency for a bullet’s tail to wobble around its direction of flight axis.  Imagine a top wobbling as it spins but traveling bottom first towards its target.  Anyone with top spinning experience knows wobbling isn’t really predictable (or much) but increases as the top slows down.  Transfer this to M855 lethality, we counted on M855 striking at an angle produced from yaw (unpredictable yaw) causing it to tumble upon striking a target creating horrific damage.  M855 production imperfections (one can’t place that steel penetrator in every round precisely at the same spot impacting center of gravity) help create yaw but not predictably from round to round.  Complaints starting in Somalia of “through and through” wounds (M855 traveled through the target relatively cleanly causing a minimum if damage) to the enemy especially at close range grew during our early years in Afghanistan and Iraq.

Further, it was noted that M855’s soft lead composition had a tendency to malform when hitting the high angle of many windshields and deflect vs. going through the glass.  This was an especially important issue when confronting vehicle borne IED’s.  Special Operations Forces and the Marines looked for munitions with more lethal effect, both adopting Mk262 at about four times the cost of M855.  The Marines migrated to Mk318 in ’09.  The Army already funded to create a “green round” decided to take a more surreptitious route to develop a more lethal round that also answered the identified shortcomings eventually resulting in M855A1.


Today, the Army primarily uses the M855A1 round while the Marines use Mk318 Mod 0 supplemented with M855.  M855A1 is the innovative result of the Army’s decade’s long effort to field a non-lead round to satisfy environmental concerns.  M885A1 is an exceptionally lethal sub 2 MOA (less than 2” spread between rounds at 100 yrds.)  M855A1 is similar to M855 “green tip” as the bullet weighs 62 grains, overall round weight is the same and is copper jacketed (except for the very tip).  The tip of the bullet is where the expansive changes start to become apparent. M855A1’s tip is bronze-colored because of the anti-corrosive coating on its hardened steel penetrator.  The steel tip is bonded to a copper slug behind the tip.  Propellant is temperature stabilized and has additives minimizing muzzle flash and copper fouling in the barrel.  The propellant creates a 13% increase in chamber pressure but ballistically is a near match with M855.

More importantly, the capabilities of M855A1 are significantly different than M855.  The round is barrier blind meaning it penetrates moderate barriers and continues on its path predictably.  M855A1 performance against soft tissue is classified but based on conversations I’ve had with ARDEC representatives at Ft. Benning during a conference they are much better than M855 and not yaw dependent.  Based on Liberty Ammunition’s T3 round upon which the M855A1 is based and observations about the steel penetrator specifically ricocheting farther than M855 I would speculate the round fragments after striking its target, causing extensive damage.  Where M855A1 really shines is in penetration.  It penetrates 3/8” of steel exceeding M80 7.62mm, the average medium machine gun round fielded to our forces.   M855A1 can penetrate some types of body armor and even cinder block and concrete to a degree maintaining enough power to wound the enemy using it for cover.  Taken as a whole this is far and above any 5.56 round generally fielded.

It’s important to digress and explore the “green round” story at this point.  As silly as it sounds, environmentalists have been successful stopping and even ending certain military training.  The Navy’s use of sonar on the Pacific coast, the loss of the only naval gunnery, aviation live fire and ground operations training on Puerto Rico’s Vieques Island and the limits placed on training areas at Ft Bragg to save the red-cockaded woodpecker have all been environmental victories that minimized or eliminated necessary military training.

The Army has serious concerns about lead from ammunition leeching into the environment and giving environmentalists “ammunition”.  This impacts training areas not only in the middle of nowhere but those in close proximity to towns or very large environmentally super sensitive parts of the country where portions of its over 500 thousand man Guard and Reserve forces train.  Sadly it’s important to address the “environment” issue early on because so much of the knee jerk negative reaction to the M855A1 stems from it.  It often drowns out the round’s significant capabilities and the ingenious way certain Army communities “used” funding dedicated for green round development to create lethality advancements and satisfy the environmental requirement.

Mk318 Mod 0

The Marines selected Mk318 Mod 0 to supplement M855 (Marines still use M855) primarily because of a delay in perfecting M855A1 in 2009.  The bullet design is an Open Tip Match Rear Penetrator (OTMRP).  The front of the bullet is open tipped (followed by a lead core and the rear half is brass).  When the bullet hits a surface, the front half of the bullet collapses breaking the glass surface.  The rest of the bullet follows through the hole created hitting the target.  It is also considered “barrier blind” against light wall materials and windshields.  The round is also rated at 2 MOA level of accuracy and is sometimes called the Mk 318 Special Operations Science and Technology (SOST) round because of its original development in the Special Operations community.


M855A1 criticism in the media, emotion and thinking backwards

There have been a multitude of articles written where hyperbole and quasi emotional arguments have replaced objective analysis.  That approach by respected publications like Stars and Stripes has had an exponential effect on the argument because they are often repeated in other media sources parroting a poorly written article instead of conducting independent reporting.  Heck, the Army and Marine Times used the same slanted story word for word.  The debate even becomes more slanted when the overwhelming majority of the media report only the counter M855A1 perspective and do not conduct the same level of analysis on Mk318.

Weak techniques and arguments disparaging M855A1

Troops have criticized M855 because it “didn’t penetrate windshields predictably and did not consistently incapacitate the enemy”.  TRUE, but we aren’t comparing M855 to Mk318!  A common weakness of many of the afore mentioned articles is they spend more time discussing M855 than M855A1.  That makes no sense since we are comparing M855A1 which doesn’t have a problem penetrating windshields (and much more) and very predictably incapacitates the enemy.

“The Marines didn’t adopt M855A1 in ’09 because it had accuracy problems”.  True and the Marines made an arguably good decision to field Mk318 which was four times cheaper than Mk262 at a time when the Army had yet to provide a round after years of development.  The problem is in these articles is they almost all fail to mention the Army fixed the problem a months later and has been issuing the M855A1 since.  Isn’t that relevant or is leaving an incorrect impression in the mind of the reader more sensational?

One of the silliest points I have seen mentioned for the Marines not wanting to switch to M855A1 is because some rifle ranges would have to be retrofitted  due to M855A1’s increased penetration and ricochet effects.  Said another way, we don’t want this new round because it’s more lethal!  When we develop a grenade more effective than the current 40mm or hand grenade will we not adopt it because training ranges aren’t built for it?

“M855A1 is a green round.”  Yes, M855A1 is environmentally friendlier than other ammunition but why is that bad?  Though mentioning this boogey man assists in avoiding actually talking about M855A1’s actual performance.  Major Glenn Dean wrote a fascinating book on the backstory of the development of the M855A1 round.  “In Search of Lethality: Green Ammo and the M855A1 Enhanced Performance Round” tells the story of how the Army’s acquisition, Infantry and Special Forces communities came together and recognized the need for a round with increased lethality and used funding for a green round to develop not only a green round but one with much greater lethality.

Almost all stories written about the M855A1 fail to address this largely undiscovered history.  I can’t comment if the lack of reporting is from a lack of researching effort or a desire to preserve unnecessary sensationalism to camouflage a lack of analysis.  It might be attributed to what Major Dean says was a conscious decision by the Army developers to not communicate M855A1’s dual requirement strategy in an effort to avoid concern we weren’t killing the enemy humanely enough.

Some writers have created a controversy over some official Army slides touting M855A1 as having  “match” like accuracy.  It was a bad choice of words to communicate the uniformity of bullet production but no worse than the Marine Corps use of the word match in describing Mk318 as Open Tip Match Rear Penetrator.  This use of the word “match” did not raise the same level of concern for orthodoxy.  In the end both rounds are rated at sub 2 MOA.

Most importantly, none of these often mentioned “issues” address any concrete lack of performance in the M855A1 round.

The best arguments against M855A1 revolve around allegations of excessively fouling and by three concerns raised by Col. Michael Manning, the program manager for Infantry Weapons Systems at Marine Corps Systems Command in Quantico, Virginia who blamed the M855A1’s high chamber pressure and exposed steel tip for eroding barrels, cracking bolts and chewing up a feed-ramps.

The source of the excessive fouling allegation is from manufacturers who submitted their weapons into the Individual Carbine Competition, a competition to select a replacement for the current M4.  The Army concluded that no new candidate met the desired and admittedly high desired performance standards.  Manufacturers were surprised at the outset of the competition by the requirement to use M855A1 when they had expected M855.  Fouling became a primary excuse submitted by manufacturers for their weapons not passing the very high Army standards.  Col. Paul Hill the Army’s project manager for ammunition said, “I had heard that anecdotal information that the M855A1 did create more fouling,” But when he arranged an extensive series of tests, Hill said, “we found…. there was no significant difference in fouling between the M855 [the old round] and the M855A1.”

The higher chamber pressure of M855A1 is connected to wearing out barrels and cracking the locking lugs on bolt faces.  Wearing out of barrels is a valid observation although it typically happens after the 10k rounds mark which is when barrels are supposed to be replaced anyway.  The occasional cracked bolt is a valid observation but as Nathaniel F. from relayed to me, “the old M855 would do that if you fired enough of it…  M855A1 stresses the bolt lugs of an M4 out much, much less still than alternative rounds like 6.8mm SPC or 6.5 Grendel.”

M855A1 is indeed tearing up uppers.  The steel tip brings upper life down from 40k to 20k, a significant cost but the same articles that mention this shortcoming do not share a new magazine follower and magazine in development fixes this problem and early testing improves reliability 300%.  This is a curious and important lapse in objective reporting.

It is worthwhile to note that Col. Manning’s concerns were based on a 2006 Special Forces torture test.  Part of the test consisted of firing 3000 rounds on full automatic.  The Naval Surface Warfare Center does small arms development for the Naval Special Warfare community notes that the bolt failures noted by Com Manning are pretty normal for hard firing regimens at 3000-6000 rounds (slide 44).  Is the program manager for Infantry Weapons Systems at Marine Corps Systems Command in Quantico unaware?  In sharp contrast to Marine concerns, Brig. Gen. Paul Ostrowski chief of Program Executive Office (PEO) Soldier said of the new round, “we have experienced absolutely zero issues with the M855A1 in combat.”

One facet completely absent from much of the main stream discussion about the two rounds is body armor.  We train to shoot center mass based on the assumption that the enemy is unarmored.  We cannot continue to follow the age old trend of fighting the next war like the last one where our insurgent enemy has largely been unarmored especially in light of the growing use of body armor.  While 2nd, 3rd world militaries and most insurgents (those who don’t get captured vests) don’t field modern plate based body armor and China isn’t really issuing all their troops body armor that is changing.  Russia is catching up and fielding effective body armor but are relative newcomers to modern ceramic armor manufacturing techniques.  We should also remember that even the best plate based armor is held together by soft armor.  In this area, M855A1 has superior penetration performance.

To date the debate about M885A1 and M318 has been highly slanted.  We would hope promised Marine testing will be done in a scientifically objective manner.  The Army’s significantly higher ammo purchase requirements and the accompanying savings should also be accounted for in purchasing any ammo in bulk.

From the previous discussion its obvious M855A1 works well against soft tissue and soft barriers e.g. windshields (just like Mk318) AND with increased capability against cinderblock, concrete and steel.  The reason the Marines continue to field the lower performing M855.  Not only is M855A1 effective against those not wearing body armor, it’s more effective against the enemy using cover and better equipped enemy wearing lower quality body armor.

Whatever round is selected, the bottom line is superior barrier penetration AND better soft tissue capability in the SAME round is a significant advantage.


Additional Research:


Liberty Ammunition T3 video through windshield.  This is a civilian round by the patent holder of the M855A1 technology.  It’s an open source perspective on effectiveness and lethality using ballistic gelatin.  It’s not M855A1 but it’s the closest unclassified info you’ll find.

The only actual objective M855A1 testing

Army Sniper Anecdote -“There is something to be said for mass and energy M855 is only 62 grs M80 is 147gr. At 300 meters M855A1 penetrated a steel target that the M80 ball could not, making it a better penetrator than a bullet with more than twice its mass and energy.”  – SFC T

Well I am an army sniper deployed with 3rd group special forces we use the m855a1 and were putting 25 out of 30 rounds in an 1/4 in steel iron maiden at 750 meters we use it in high heat of Afghanistan at 8000 feet and in 34 mile per hour full value winds I love the round it shoots straighter than the 77 grain LR rounds it&#039s better than green tip only issue is it penetrates to well with little to no expansion but it will penetrate glass like paper and it goes through a land rovers quarter panel and engine block pretty easy for those ISAF guys that have strict roe it&#039s great you&#039ll stop a moving vehicle quiet easy it just takes better shot placement to get your enemy down because it pokes small holes but suicide vests Kevlar even our issued plates don&#039t stand up against these rounds I like lead because it puts the enemy down easier with half assed shot placement in a fire fight that&#039s how it&#039s gonna be but I love this round maybe we get better ammo who knows but it&#039s pretty awesome stuff push out to your weapons max effective with thirty rounds see if you don&#039t like it shoot at iron maidens shoot things made of metal you&#039ll find out too that it&#039s a very dangerous round just be aware where you shoot cause it goes through every thing. – Anthony Kirkpatrick

Magazine replacement slide 5

M855A1 presentation

M855A1 History by Plaster

Acknowledgement: I’d also like to acknowledge Nathanial at the firearmsblog who provided some unique and outstanding insight on the issues I wrote of.  The article would not have been as well documented without his input.  I encourage a visit to the blog for knowledgeable and objective assessments.

Be Respectful, Candid and Pertinent. No Posers, No Trolls…
  • engelbrad

    Great write up Will!
    I also appreciate the “additional research”. It’s great to read something from a writer that works hard to present facts and educate.

  • engelbrad 
    Thanks, always enjoy feedback and I always walk away with a sense of accomplishment when readers learn something.

  • YankeePapa

    …Much nonsense written about firearms and ammunition.  Some writers (who should know better) seem to have taken their lead from the works of the prolific author of “The Executioner” series and others.  Spoke of the automag pistol that could cut a man in half at 50 yards with “fine buckshot”  (sandshot?) 
    …At the moment it appears that both services have a round with which they are happy.  If economy is the issue then an independent, highly qualified, and objective evaluation group should run unbiased tests.  (Maybe a simultaneous expert comparison of MARPAT and the Army’s latest effort…)  Objectively chosen winners to be used by both services…

    …Ca. 1973 I was present at the Seattle Police Academy when multiple agencies present regarding a demonstration of ammunition used by various departments and agencies in the region.  A car was towed onto the range by a local towing company.
    …One round at a time a demonstration team gradually shot up the defunct vehicle.  First round was from a standard police .38 revolver firing regular ammunition.  The first round glanced off the rear window of the vehicle.  Shooting at the driver’s door the rounds penetrated the outside layer of metal… and pretty much dropped just beyond.  
    …Seattle Police had recently switched over to “Super vel” ammunition (this was long before they adopted the Beretta) and it was demonstrated.  While it shattered the rear window of the vehicle… there was essentially nothing left to impact anything in the rear seat.  
    …The demonstration went on for quite some time.  Naturally 00 buck and 1 oz slug loads gave a better account of themselves.
    …The #2 of one small department (sent by his boss) got to boasting about the “hot loads” that his department used… Specially prepared by a friend of the Chief’s.  He held out a few rounds to the head demonstrator.  
    …”I won’t fire that in my pistol, but I will try it with yours.”  As I recall, six inch barrel .357 Magnum pistol.  The only round fired bounced feebly off the car door…  All the reps of the other departments and agencies were appalled… Doubtless the Chief found another source of ammunition.
    …The fact that a quality round developed because of PC issues is of no consequence.  “Illegitimate” parentage is not the measure of a man… or a bullet.  Of course the radical environmentalists have been causing grief long before most of us were born… (Got the National Park Service to refuse to permit radar installation on highest point on Oahu some time prior to the attack on Pearl Harbor to avoid “disturbing” a bird sanctuary…)  

  • Joshua75

    The M3 Pmag is another viable option. The Army actually tested it and that is what led to the design changes we are seeing being implemented in the GI magazine, which will still be inferior to the Pmag.

    In my talks to Magpul the M2 is also fine, just not tested with M855A1 like the M3 has been and the M3 has more advantages like actually being rated down to -60 and what not.

  • Joshua75 
    I wonder how they do on the improved reliability scale?

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  • JaredMaxwell

    It is painfully obvious the author has never read the DA-PAM.

  • JaredMaxwell 
    Oh, I’ve read quite a few.  Put the beer down and be specific.

  • KevinHarron

    Nice article.  Followed the link from TFB to here.

  • KevinHarron 
    Appreciate your comment and taking the time to visit. Thanks.

  • Joshua75

    Not sure. The Army claims 300% increase in reliability over the tan follower magazines. However I haven’t actually seen the finished product of these pmag imitating aluminum GI mags yet.

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  • mksmith76g

    There are a couple of problems not listed in your defense of the M855A1 round. First, stating that the M855A1 performed better through 3/8 inch steel at 400 yards than the 7.62 M80 round is misleading since the M855A1 is an AP round and should do better going through steel. Now if the 7.62 NATO AP round was used and not the standard lead core M80 round the story would be much different. Lets make sure we compare apples to apples. Next, the cost of the M855A1 is avoided in every story written on the subject and for good reason since it is so expensive to produce and cost multiple times what the current M855 cost or even the M855 AP round would cost if used in place of the M855A1. With the military having to look at budget cuts that are sure to come in the future using a way overpriced round of ammunition has to be look at very closely since hundred of thousands of rounds are fired each year even in times of peace. And it takes millions of these over priced rounds in a time of war. Money doesn’t grow on trees my friend not even for the military. The military already has a 5.56 nato AP round that can do the same job that the overpriced M855A1 round is being asked to do at a fraction of the price and without the overpressure problems and increased wear to the rifles. The only change that would need to be made to the current 5.56 NATO AP round would be to replace the small amount of lead currently used in its production with zinc or aluminum. Also the M855A1 will have the same problem with passing through someone that is of a thin build that the M855 round does now, physics just doesn’t change because an exposed steel tip is placed on top of a copper slug. Last but far from least is that the same ballistic gel test that were done on the M855 and showed it was the answer to all the earlier bullets problems but was then fielded had the problems that it was said to correct and once again raised its ugly head. The real problem here that needs to be addressed is that the 5.56  NATO round is a great for shooting small animal but it isn’t an effective deer and elk round. Humans are more the size of deer and elk and the US Military needs to field a round that is effective for the pray that is being hunted. And when the pray your hunting can shoot back at you if your first round doesn’t stop their ability fire their weapon then does it really matter if the round your using is “Green” or not at that point. One last point, when the military used the 30-06 round in WW2 and later used the 7.62 x 51mm NATO round in later wars we didn’t have discussions if the ammunition our military used was effective or not. Maybe we should back up to when there wasn’t a problem and ask the question of what changed and made the problem we have now.

  • mksmith76g
    Thanks for your post but I disagree with a lot of your positions.
    M855A1 isn’t an armor piercing round.It does not have a steel penetrator and if
    one reads the numerous background links one will see that AP capability was not
    a requirement.Will M855A1 penetrate
    steel?Yes.So will M855, M193, Mk318 and even 7.62 M80
    ball to a lesser extent.Penetration ability
    alone doesn’t make a round AP.Open tip
    rounds sometimes act like hollow points but they aren’t hollow points.M855A1 typically fragments when it hits its
    target.That doesn’t make it an
    explosive or frangible round.This
    article might help you understand what makes a round AP:

    What do you think M855A1 costs?My sources at PEO Ammo and ARDEC have said the price is
    comparable to M855 and Mk318.Changing
    lead for aluminum or zinc in a round isn’t
    as simple as it sounds. The weight of the round has a major impact on
    how the round flies and on terminal effects on target.
    M855A1 doesn’t over penetrate like M855.Quite the contrary, read what I wrote about
    yaw and terminal effects on target.Reports
    from theatre suggest no such problem.(I
    also discuss the overpressure problem e.g. barrels are typically replaced
    before reaching the tens of thousands rounds it takes for the barrel to
    fail.If we replace barrels at 10k
    rounds and M855A1 makes them fail at 20K the point is mute.)
    There are a multitude of reasons we left 30.06 and 7.62 as
    the round for the rifleman’s primary weapon.Almost 50% cut in weight (direct impact on resupply and the ability to
    provide sustained suppressive fire), ability to control on fully automatic both
    come to mind.A bigger bullet will
    always be more effective but for the overwhelming majority of firefights 5.56
    has proven to be effective.The fielding
    of Mk318 and M855A1 has stopped the through and through problem. M855A1 is very capable of one shot stops based
    on reports coming back from theatre one of which I included.BTW, generally 7.62 goes through flesh even
    more so than 5.56.

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  • lynnfaris

    What a good write up! Took me a while to read all of the info.Actually, I like guns and ammo not because I am into the military job or something.But I love to play shooting games and mostly first person shooting games like Call Of Duty, Battlefield, Counter Strike and etc.So this article give me a lot of info.If I got a chance i want to hold a real rifle and shoot it.But it will never happen, because i failed a basic military training, and never got a chance to do a military service.When i played COD, one of the weapon that i like to use is AR15, i really do not know, how good or how real the game portray the realistic of shooting power.As far as I concern, Full Metal Jacket ammo is good for general shooting and hollow point is great for long range shooting.Friend of mine at  told me about the AR15 still used by the soldiers.

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