Army M4 vs. Marine M16A4

There is an interesting article at Human Events about the US Army culture favoring the M4, while the Marines culture being pro-M16A4.

Two years ago when I was in Iraq, I noticed there were essentially two different primary infantry weapons (the M16 automatic rifle and the also-automatic M4 carbine) carried by America’s two primary ground forces — the U.S. Marine Corps and the U.S. Army.

Marines for the most part were carrying the M16. The Army on the other hand was primarily carrying the M4: a shorter, lighter version of the M16 with a collapsible-stock.

Hat Tip: Say Uncle

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • John Pollard

    Having served in the infantry in both the Marines and the Army, and having served in Iraq 2005-2006 in an army mechanized infantry platoon with an M16A4, I concur with the author’s assessment. Nearly every Army infantry soldier in Iraq patrolled in humvees or otherwise had a permanently-assigned seat in a vehicle, while Marines see vehicles as merely a way to get from one foot patrol to another. Humvees are cramped (despite their size) and a 39-inch rifle is difficult to get in and out of the vehicle. The problem is much worse with up-armored humvees, which have more restrictive door openings. For troops that see the humvee as home, the M4 is the way to go. In Iraq, I patrolled in Bradleys, and never minded having the longer M16A4, because there was plenty of room for it, and the former Marine in me liked having the long barrel…

  • Dave K

    That’s because the Army is for weaker smaller men who couldn’t be Marines, thus they need a smaller gun. The Marines on the other hand can handle a full size rifle. Oh that and they actually like to hit their targets.


    • I wonder if the reason is that the Marine command don’t have the budget or desire to spend dollars in new M4’s.

    • what is wrong with you?
      army put there lives in danger for our country too
      they were the first branch also

  • Fred

    Despite Dave’s incorrect above thoughts, large chunks of the Army still use M16s. The Unit I was with up till a year ago was using, and still uses, M16A4s, with a scattering of M4s for Lt’s and drivers and that’s about it.

    The more interesting aspect of the article in my mind is the mentioning of the current rifle being the plateau of rifle design.

    • Matt. I don’t believe you were ever in the Corps. Plain and simple. Marines don’t bash their own family on the net. The Army marksmanship isn’t even close to the Corps. The Marine Corps is the only branch in the world that qualifies at 500 yards open sights. Also, Marines that transfer over to the Army say that they made a mistake and the Army doesn’t have the discipline the Corps does.

      The Marine Corps chose the M 16A4 because of reliability, accuracy, velocity. The Corps has M 4’s but a lot of grunts use M 16A4’s. It was not a money thing. When the Army went with the M 4, the Corps went with the A4 and M 4’s on a smaller scale.

      This is a real active duty Marine speaking. Master Gunnery Sergeant Brooks.

      • FredC1968

        As an Army Veteran, the USMC puts more time and resources into marksmanship training than the USA. In 1987, I qualified to approximately 300m. The Marines qualified to 500+ m.

  • Matt Groom

    As a former Marine, let me assure you that the main reason you don’t see as many M-4’s as you do A4’s is because the USMC spends more money on recruitment posters than they do on rifle magazines. The USMC doesn’t have the money to spend on M-4’s because they spend too much money on television commercials.

    As a former Range Instructor of Marines, let me assure you that there are a number of Marines who couldn’t hit the broad side of a barn and they are incorrigible. We called them “UnqSperts” because they were expert at failing to qualify, no matter how many extra rounds you slipped them on the 500 yard line, or how many extra relays you gave them to shoot.

    Some of the best Marines I knew were guys who had served in and disliked the Army, and most of the best Marines I knew got the hell out because they disliked the USMC. Some of those guys joined the Army and some of them joined the Air Force, and a lot of them became Law Enforcement.

    Personally, I would much prefer an M-16 for most things.

  • Pat

    hey Dave…I have a 31 year old brother who just got top gun and honor grad in sniper school at Fort Benning… and from my understanding, that was the first time in 10 years… oh…and he is Army…don’t lump all the rocks into one bucket while having a diamond in the rough at the bottom

  • Interesting commentary. I would be surprised to hear that Marines tend to break M4’s but not A4’s. Marines can be hard on anything.

  • jdun1911

    Military traditions is one of the hardest thing to break so it better not to fight it.

    These military traditions goes back to the founding of Army and Marine Corp. The Army have their way of doing things. The Marines has theirs.

  • solomon

    Marines still use the M16A4 because its part of the Martial Arts/Close Combat Program. I forgot what the exact quote was but many of the basic movements are performed with the butt of the weapon. The M4 is good to go and serves its function well. I think the point about the Army being highly mechanized (like someone said before) dictates this more than anything. Aren’t they suppose to be getting even more Stryker Brigades? As a side note a bunch of Marine Gunners are suppose to be lobbying the Commandant to get the collapsible butt stock for the M16A4…supposedly the Commandant is resisting because of the hand to hand issue.

  • Michael

    What year did the M16A4 come out? 1994, or earlier??

  • Brad

    I don’t remember where I saw the article, but it was more than a year ago (maybe two?), where the USMC was evaluating what to replace the M-16a2 with. At the time the Army still clung to the XM-8 as an ‘eventual’ replacement weapon, but the Marines wanted to replace the M-16a2 immediately.

    The candidate weapons under consideration were the M-4 and the M-16a4. Supposedly tests demonstrated the longer weapon as more reliable and that was the primary reason it was selected in preference to the M-4.

    • FredC1968

      I found that the gas impingement system works better with a full sized gas tube.

  • Ken

    Damn, I’m not that old, but I was issued the M16A1 back in 1984. There were still some of those POS rolling around in the armories. I would have given a testicle for an M16A2, let alone A4 or an M4 carbine. Times change.

    • FredC1968

      There is nothing really wrong with a properly maintained M16A1.

  • Rob

    My brother just came back from marine ocs and they were the first class to train with the m-16a4 he says that it comes equiped with a fully automatic mode along with a three round burst, just like the m4 but has a better effective range and reliability than the m4.

  • StrykerGunner

    Last time I checked and I’ve been in the Army infantry for the last 6 years. Aside from SF standard issue A4s and M4s are not full auto. just sayin

  • Dave Wood

    About Matt Groom’s comment, I know the requirements for a US marine and they need to be acurate with the M16A4 at 500 yards and greater. They also spend more time in training at the range than any other branch of the United States military.

  • Sgt Peterson

    Marines are using the M4 in Iraq and Afghanistan …my last deployment we had them, and people who didnt have them were admin Marines…..why did it take the Marines so long to get these weapons??? Ever try and convince a Marine he is wrong? Especially an old Marine? Good luck. The other reason is funding, we get the smallest piece of the DOD budget pie. Were used to using less to do more than everyone else. As for the M16A4’s go, just about everyone I knew wanted to toss them in a ditch and get their A2’s from boot camp back haha.

    • Sgt, why did they want to ditch the A4? Weight?

  • Mike

    Facts is facts fellas……..
    The M16a4 has better stopping power and better range than the M4. Could someone who is a great shot qual on the 500yd range with an M4? Sure, but a few things make that a moot point.
    1) The same dude, shooting an A4 would do better 10 times out of 10.
    2) The M16a4 sends it’s rounds downrange at a higher velocity than the M4; I’m not an expert in physics, but from what I do know, that equals more “oomph” when hit hits.
    3) This is just my personal experience; the M16A4 is simply more reliable than any shorter barreled version. If I had to guess, I’d assume that this has something to do with a more powerful buffer spring, and a gas recoil system that has a full barrels worth of gas to tap into.
    There is no doubt that the M4 is lighter, but the difference in weight isn’t huge. Also, while the shorter barrel does make the weapon handier, it doesn’t change the fact that an MP5 is shorter that both…..and I don’t hear a huge clamoring to make THAT the primary weapon.
    My thoughts, the M4 is sexy. The M16A4 will kill better.

    • Josh Drake

      The m4 has a negligible decrease in stopping power compared to the m16. Both fire a 5.56. And in addition the m4 was fielded with more lethal ammunition.The 5.56 round only loses about 250 fps of muzzle velocity out of an m4 from an m16. M4s are actually quite capable of hitting targets out to 500 yds. Shorter barrels experience less “barrel whip” than longer barrels do, thus allowing them to be more accurate than most would think.

      USMC rifle expert x3 and avid firearms researcher

    • Josh Drake

      However the m4 is over gassed compared to the m16 which uses a rifle length gas system. Rifle length gas systems are lighter recoiling and put less stress on the internal parts. The m4 having a carbine length gas system increases the power and speed of cycling, causing more wear on internal components.

      Kinda like a 9 mil handgun rechambered for .40 Stuff just wears out faster.

  • Brian

    The way i see it is this, it simply comes down to physics and the role each service plays in combat operations

    The A4 has a longer barrel this affords it two things the shorter M4 doesn’t have 1. more time in the barrel means higher muzzle velocity. 2. The additional time in the barrel also means the bullet is spinning faster when it is ejected from the muzzle both of these factors gives the A4 higher accuracy and more kinetic energy at longer ranges.

    The primary mission of the marine corp is amphibious assault and immediate action (typically 48 hours on less) meaning the Marines are first to fight and conditions in the early stages of a war favor M16A4. When your are storming a beach you want that ability the blow the enemy machine gunners head off at 500 yards. With only 1 sq foot of him exposed between the sand bags.

    By the Time the army arrives the situation has changed now the enemy is retreating hiding urban warfare is what you are most likely to encounter, conditions favor the M4 with a shorter barrel it easier to get in and out of vehicles building a what have you additionally engagements are at closer ranges the higher long range accuracy of the A4 is not required as often.

    So both weapons serve each branch in their particular roles best that is not to say that their isn’t some overlap of missions where soldiers or marines might be better served to have the other weapon but from a overall perspective and looking at the Primary Missions of each branch the M4 best serves the Army and the M16A4 Best serves the Marine Corp.

  • ME

    Oh boy some of the infamous internet commandos are in full force on this post. Sheezzz!!

  • Logan

    Which rifle is more effective?

    What is the primary rifle of the
    Air force

    And how many more years will they use it primarily

  • Tyler

    The main reason the Army uses more M4’s then the Marines is yes, They operate in Humvees more. But the Marines live in them just as much as the Army does. The Marines are usually the last ones to get the good stuff, And are usually the shortest on budget, So they use what is more available… Not because they want more posters then mags. But when the Marines do get a chance to get their own things its usually important. Like marpat or the new Amphibious shit coming out in a few years. But let me assure you both branches use both the M4’s and M16A4s.

    • JM@MoVal

      M16A2 back in the 90’s; Dragon missile, and demo is what I knew. I now I have an AR15 w/ 16″ heavy barrel. I prefer the 20″ inch barrel that my A2 pea shooter had though. I could hit 9/10 times out to 500 mtrs. It was more accurate, didn’t jump as much popping(quicker follow ups); and the flash w/ compensater wasn’t as bright/loud as my 16″ barrel AR15. I am building a second now and it will be a 20” barrel, but not sure about the stock yet; since I do like an adjustable stock. However; I do like the fact you can put cleaning gear on the fixed butt stock. BTW, it is easier to maneuver my AR15 around inside.

  • i probably have no clue what i am talking about because i am only twelve but, i would choose the m16a4. it has the longer barrel which means more effective range. i would think the m4 would be better for vehicle operations but, even though a lot of people say the m4 is better in cqb i would differ. i have an airsoft m16a4 and i can easily maneuver it in small spaces. i like m16s more too because of the long barrel because i have always liked long range.

    also, i like the army more even though they use more m4s.

    ps: is it really common to switch branches of the military like that?
    and for the people who have please say which you like more army or marines.

    • Cole

      Chuck, the favoritism toward one branch or another is completely based on the mind set of the individual. Marines are more prone to be adventerous and in search of action. Soldiers in the US Army, though some are like that, mostly are not the same gung-ho insanely motivated tunnel-visioned killers that Marines are. Both Army and Marine Infantry have true warrios fighting for their country, but many times the Army, because they have much more people, are able to afford comforts, namely expensive technologically based equipment and unlimited funds to do so. This causes them to be a little more lax on their training. The Army also has a wider range of occupational specialties, again because of numbers and funds, but Marines have a more combat oriented training style and everything they do revolves around the Air-Ground combat elements. It’s also important to note that the Army gives a large signin bonus, which is motivation enough for many people.
      For me, however, the USMC is the life of trial and beauty, so it’s Marine Corps all the way.

      • HSR47

        To clarify, they each have different operational goals, and they each have different budgetary concerns.

        The Marine Corps is smaller, and their budget ends up being a line item on the Navy’s budget. To understand their focus on “every man a rifleman” it helps to think of them as a Navy MOS.

  • Fernando

    Yes the m16a4 has way more muzzle velocity and will punch harder and longer than an m4. I understand the use of the m4, but now both Marines and Army are moving completly towards the m4. Not all combat occurs in close quarters, in Afghanistan engaging distances vary widley, but in the mountainous terrain, its well over 400 meters so the m16a4 would be way better for these types of engagments.

  • Michael Fournier

    Depends on the mission in a urban engagement clearing rooms and moving through tight spaces and and entering and exiting vehicles a M4 is the better choice. There should NEVER BE one weapon fits all it should really be mission dependent and the MOS of the soldier. IS he in a support role who weapon is mostly to defend if attacked or a forward assault unit like a Ranger or Spec ops unit?

  • G3Ken

    I know it’s an old comment, but in response to ROB May 24, 2010, I am on the phone with my son at this very moment who is at USMC OCS in Quantico (end week 5) and they are using the M16A4 and it is “burst, semi,safe”. NO full-auto. He says “I’m sure because I have to say it a hundred times a day”. Just sayin’

    BTW, pray for my boy to succeed through his last 5 weeks!

  • M16A2 M16A4

    I have a cousin in the US Marine Corps and he tells me both the M4 and M16a4 are three round burst and semi automatic. And from the information i have gathered over the past few years i would probably take the M16A4 into battle. It has more stopping power, more muzzil velocity and is more accurate. It is also more reliable. My vision is screw the M4, rock on M16a4! Screw the AK47 too!!!

    • officer candidate

      The m4 has been produced as a s-1-3, s-1-3-f, and s-1-f. weapon. the M4A1, used by special forces, Rangers, SEALs, and others, is a safe-1-auto. The M16a4 is s-1-3 for the US military, but has been produced as a s-1-f as well. The M16a3 is a s-1-f.

    • HSR47

      The fire modes of any rifle based on the Armalite Rifle 15 (Read: any M16, any M4, any AR15) are solely a factor of the trigger group components that are installed.

      All told, there are four basic factory configurations I am aware of:

      *Two position Safe/Semi
      *Three position Safe/Semi/Auto
      *Three position Safe/Semi/Burst

      *Four position Safe/Semi/Burst/Auto

      The first is a non-machinegun variant. It lacks the autosear, the associated pin hole, and has none of the appropriate catches/notches on the hammer/disconnector/selector.

      The second is the original machinegun variant, and has a fairly simple autosear arrangement.

      The third is a modified version of the second, including a cam wheel on the right side of the hammer, and a second forward hook on the disconnector to interface with the cam wheel. The disconnector doesn’t grab the hammer unless the forward hook is in one of the two deep notches on the cam wheel. This means that when you set the rifle to burst, you will get one to three rounds depending on which notch is engaged on the cam wheel.

      The third is a hybrid of the second and third, including both disconnectors, and extra cuts on the selector lever to be able to select between either disconnector (left/single hook only for semi, right/double hook only for burst, and neither for full auto).

      If you want to the workings of these trigger groups more in depth, and with pictures, go here:

      Still that being said, you can put either type of three position trigger group in ANY AR-15 pattern lower that is configured as a registered-receiver type machinegun without any permanent modification to the lower. installing a four position fire control group however, generally requires either milling to remove the selector stops, or using a special selector lever that floats above them.

  • M16 Ftw

    From the Army personel i’ve talked with, none ever even touched the M16A4. Maybe the A2 at most.

    The M16A4 has been proven the better rifle: faster velocity, greater accuracy, and more than 200 yards extra effective range. And thats just cause the longer barrel. Most of the time your engagements are at a longer range. Now the M4 obviously is better for the close engagements in a CQB enviroment technically, but i’ve operated the the M16 and the M4 in Close quarters and haven’t had a problem with the M16. In fact, i prefer it. If i come up on someone i can hit them with the butt of the weapon or, if i have a bayonet fixed i can have a meter of reach on him.

    So, the M16 is a better rifle, why doesn’t the Army use it? Well the Marine Corp Infantry focuses on infantry combat on foot, what infantry combat is, but the Army views infantry as people paired with vehichles. Army uses the vehichles with infantry inside, whereas the Marine Corp uses infantry with the support of vehichles, cause infantry is the base of it all.

    Now also, another reason the Army might not be able to get the M16 back if they wanted is that they are a 1 million strong force, and switching even half that many guns put is hard.

    • They did a study about most combat engagements being under 600 meters or something…if *most* engagements were long distance then we would most likely be using the M14 and M16 still…the matter of the fact is that the M16 is fine until you go into a building, I mean I can use an M16 length rifle inside but I would prefer my barrel not hitting walls and having to lower the damn thing every time I go through a doorway or whatever…the M4 is far more versatile, I think the length is perfect, hell Navy took it even FURTHER with DEVGRU and some regular SEAL units and made the even more compact Mk.18 which is basically a chopped down M4. Ask anyone who’s been in a CQB scenario about rifle length, I can deal with a heavy rifle but dealing with length is a pain. I think you’ve made some generalizations about both the Marine Corps and Army, they both have a variety of versatile forces, you’d be hard pressed to make such general statements. Besides the M4 has been received very nicely among many of the units employing them, it started off as a must for Special Operations Forces, Airborne units, NCO’s and Officers and then it just spread…I think its one of the few things the US Army got right :P!

  • Vince

    I keep reading Army is using M4 we had an opition what we wanted to draw was in 1st AD 2nd BCT i was issued an M16 , M1A1 , A2 so on was a few guys with M4 the shorter barrel is a great gun for clearing buildings , i prefer the M16 stopping power from further distance was semi and auto , is rare use auto ever when on foot in the suc, waste of ammo every bullet i shot had someones name on it , auto pretty much suppression fire,
    read few comments about army being attached to vehicles , well i guess they did give us a ride there lol and picked us up, think marines got same treatment , i take nothing away from my brothers in arms the earn any and all respect the get , far as the navy and AF goes it takes all services to make any one operate effectively and with minimal loss,

    Bottom line all fighting for same thing and to all those who have served that never deployed who may have been in rear helping family members and junk just as important to me as the guy who has my back , if i am worried about what is going on at home ( on base ) mind not in play nothing good comes from that , Support our troops always stand behind them ,, if you do not stand behind them ,, please by all means stand in front. God Bless Everyone

  • Da boys

    Marines, the offical sponser of the word M sixteen a four.