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A2 vs A3 vs A4?

Discussion in 'Rifle Country' started by groover000, Apr 11, 2008.

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  1. groover000

    groover000 Member

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    I have tried searching for this but I am getting no results. What is the differences between an A2, A3, A4 on ar-15 rifles? Pics would be helpful if you have them. Thanks in advance.
     
  2. Matt-man

    Matt-man Member

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    According the military designations of the M16 series:

    A2: Fixed carry handle. Safe/Semi/Burst fire control group.
    A3: Fixed carry handle. Safe/Semi/Auto fire control group.
    A4: Detachable carry handle/flat-top receiver. Safe/Semi/Burst fire control group.

    AR-15 vendors frequently get A3 mixed up with A4 so you often see flat-top ARs called A3s.

    Check out the Wikipedia entry for the M16 for additional info.
     
  3. BBroadside

    BBroadside Member

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    So for ordinary civilian (i.e., semi-auto-only) purposes, the A2 and A3 are much the same? I see people making references to "A2 style sights" so now I guess they're contrasting them with A1 rather than A3/4-style sights.

    Here's a pic of an A2 sight.
    And a (frustratingly small) one of an A1 sight.

    Incidentally, I ran into the Civilian Marksmanship Program's competition rules on the subject today. Looks like removable carry handles are okay; it's just the "flat-top only" upper that are a problem. Also it implies that the A1 has a short buttstock than the later ones (not mentioning telescoping buttstocks which I gather aren't really M16 items per se, but rather CAR-15 / M4 furniture).
     
  4. DMK

    DMK Member

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    Matt-man's got it. For civilian rifles, A3=A4. The A3 is a misnomer really. Civilian manufacturers came up with it before the military adopted the M16A4.

    A1/SP1 rifles have a round front sight post with 5 adjustment clicks.

    A1/SP1 rifles have a rear aperture with two small holes. One is set higher than the other so you can flip the sight back and forth for a close range and a long distance zero. The rear sight is not otherwise elevation adjustable. The windage adjustment must be made with a tool or the tip of a round, and it locks in place.

    All later rifles (A2/A3/A4) have a square front sight post with 4 clicks.

    All later rifles with both fixed (A2) and detachable carry handles(A3/A4) have a rear aperture with one of the holes much larger (a ghost ring). You can still flip the aperture back and forth for a close range and a long distance zero, but the close range sight is the large ghost ring. The rear sight is elevation adjustable with a large range marked ring below the sight. The windage adjustment are made with a thumbwheel.

    When one refers to A2 sights, they are referring to the later sights, or merely the later aperture or front sight post.

    Vice versa, when they refer to A1 sights.

    It gets really confusing when you refer to military contract carbines. Before the M4 carbine was standardized (which uses A2 sights BTW), Colt designed carbines with a seemingly random combination of features.

    Another point of confusion is front sight bases. Military M16A4s and M4 carbines use taller 'F' marked front sight bases. This is because Colt designed the removable carry handle to be taller, (not because of barrel length which is what many folks say is the reason). Most civilian rifles, flat top or not, use standard height front sight bases. Some companies, like CMMG offer 'F' height sight bases as an option. With a standard height sight base and a carry handle, you may require a taller front sight post. Often times not.
     
  5. Creature

    Creature Member

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    A2 is on the top, A3 is on the bottom:

    [​IMG]

    A4 as descibed by Matt-man.
     
  6. Bartholomew Roberts

    Bartholomew Roberts Moderator Emeritus

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    Creature, your description is incorrect. Technically speaking, since we are discussing military nomenclature, the top rifle is not an M16A2 and the bottom rifle is not an M16A3.

    However, even if you were just using the term loosely to describe the upper receiver, the top one would be an A2; but the bottom would be an A4.

    Matt-man described the military nomenclature and the manufacturer confusion very well.
     
  7. Matt-man

    Matt-man Member

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    I stole these photos from FN. They have the rifles labeled correctly, which is no surprise since they produce them for the US military.

    M16A2:
    [​IMG]

    An M16A3 would look just like this except it'd have a "FULL" position on the selector instead of "BURST."

    M16A4:
    [​IMG]

    You often see A4s accessorized with things like optics, like this:
    [​IMG]
    USMC M16A4s get a Knight rail system like the one shown here (this is actually an AR-15, it doesn't have a 3rd position on the selector).
     
  8. pgeleven

    pgeleven Member

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    wrong. the larger ring is for night shooting when your pupil diameter increases you are not able to use the day sight (smaller ring). its not a 'ghost ring for close range'
     
  9. DMK

    DMK Member

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    No, I'm right. The larger ghost ring is lower than the smaller peep. It is a close range sight. The small peep, being higher, is for long range use.

    Soldiers are taught to look over their sights for night shooting.
     
  10. pgeleven

    pgeleven Member

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    according to TM 9-1005-319-10 (our operators manual) its a night sight. we aim with the muzzle for close range, both soldiers and Marines. regardless, the sight doesnt need to be lower, it will hit a 30 meter target on the same level as a 300 meter target.
     
  11. 41magsnub

    41magsnub Member

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    We were taught to use the larger ring for night fire and while in MOPP gear in the Army...

    We zeroed with the smaller ring.
     
  12. DMK

    DMK Member

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    OK, so maybe it is used at night too.

    The two apertures still zero at different ranges, with the larger one zeroing closer than the smaller one.
     
  13. pgeleven

    pgeleven Member

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    we never zero'ed with the larger ring, it would contradict all PMI's on sight picture/sight alignment that we have ever been taught. don't take this as a pissing match DMK, its the first rifle i had in the military and carried for almost a decade. i almost felt like you were telling me something about my wife that i knew wasnt true.
     
  14. DMK

    DMK Member

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    I never said one should zero the rifle with the large ghost ring.

    What I said was that the ghost ring is lower than the small peep. If you zero with the small peep (as you should) and flip to the large aperture (without changing the elevation ring), your POI will be lower. ie, the round will cross zero at a closer range with that aperture than with the other.

    For example, I use an A2 aperture on my M16A1 upper. I zero the rifle with the small peep at 200 meters (219 yards), IBZ. When I flip to the ghost ring, I get an approximately 100 yard zero.

    My only point was simply that the apertures are different heights when you flip them. Maybe this isn't the way the .mil tech manuals describe it, but it's true. Try it yourself if you doubt me.
     
  15. Onmilo

    Onmilo Member

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    I qualified numerous times on the Army Rifle Qualification Course which has pop up targets to 400 meters.
    You use the fine apeture and shoot from a foxhole position after zeroing the rifle with the fine apeture using the twenty five meter zeroing target.

    Qualifying on the Army Combat Rifle Course, I was taught to move and shoot at pop up targets to ranges of no greater than 125 meters.
    You are instructed to use the large apeture sight as a ghost ring and this is after prone fire zero of your weapon using the small apeture and 25 meter zeroing target.

    Qualifying on the Urban Warfare Combat Rifle Course featured live fire in tire houses with ranges no more than forty feet and you are taught to look over the rear peep and aquire the target with the front post only.

    Bear in mind I qualified on these courses twenty five years ago but knowing the Army, not a whole lot has changed.

    The M16A4 flat top is arguably the best version of the long rifle to date.
    The burst fire selector is not really necessary because everyone is taught to use the rifles as semi auto.
     
  16. Creature

    Creature Member

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    I stand corrected. Thanks!

    How is it that the majority of folks in the civilian AR industry have it all wrong when it comes to describing A2 and A3 uppers...and why does it persist?:

    http://www.ar15.com/lite/topic.html?b=2&f=186&t=147417

    http://cmmginc.secure-mall.com/shop/index.php?shop=1&cat=30

    http://www.bushmaster.com/products.asp?cat=6
     
  17. DMK

    DMK Member

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    They aren't incorrect when describing A2 upper receivers. The fixed carry handle with the elevation wheel is identical to the upper on the M16A2. Although, if you really want to get technical, an A2 upper assembly should not have an HBAR barrel. It would have a 20" Govt. profile (lightened under the handguards) with a 1/7 twist and chrome lining.

    As far as civilian A3s are concerned, the civilian manufacturers started selling flat top uppers before the military adopted them on rifles (although they may have had them on carbines already, I'm not sure when Colt started shipping flat top M4s). There were only the A1 and A2 rifles, so the marketing folks decided to sell flat tops as A3 rifles (because it sounded cool to them, like tactical does today). Once a term gets widely used in this industry, it's hard to shake.

    Are they wrong? They make the rifles, so who's to say. They could market them as Martian ray guns if they wanted. The differences between 'real' military M16A2 and M16A3 Assault Rifles is moot because all new manufacture civilian ARs are semi-auto.

    Here's an AR15 clone of an 'M16A2'. I could call this an AR15 clone of an 'M16A3' too. The military M16A2 and M16A3 look identical. This same rifle with a flat top receiver (removable carry handle) would be an 'A4', but could be referred to as an 'A3' by some manufacturers of civilian rifles. Confusing? yea.
    [​IMG]
     
  18. aloharover

    aloharover Member

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    So you were using the M16A1 not the A2?

    FWIW rifle ranges at Benning, Stewart, Hood, Polk, Irwin, Lewis, Schofield, Dix, Ap Hill, Indian Town Gap, and Drum are all 300m Pop-Up.
    The Army FM on Marksmanship has listed the course of fire tables since the 1970s as 50-300ms
    The Army popup qualification course has you shoot 20rds from the foxhole, and then 20 prone unsupported.
     
  19. Bartholomew Roberts

    Bartholomew Roberts Moderator Emeritus

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    My guess is that the M16A3 is a very obscure designation. I think it is only used by the Navy and there are very few in existence. As a result, most manufacturers were probably not aware it existed. So when the flattop came along as the "next generation" upper in the early 90s, a lot of them started calling it an "A3" upper.

    I think it continues to persist because a lot of people use that term for flattop uppers now and the M16A3 is still an obscure weapon.
     
  20. chauncey

    chauncey Member

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    hate to tell you, but "pgeleven", who must be a jarhead, is correct.

    your confusion may be based upon some earlier battle rifles, like the Savage-produced Enfield, that has a 300-yard aperture and a 600-yard aperture. the elevation of the sight changes, but I can't remember if the size of the peep gets bigger or smaller.

    I can recall, that when shooting while wearing a gas mask, it didn't matter what sight I used, I couldn't hit squat. night shooting wasn't much better.
     
  21. DMK

    DMK Member

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    Chauncy, I don't know what they were teaching you folks in the military, but the elevation does change when you flip the A2 aperture.

    http://groups.msn.com/TheMarylandAR15ShootersSite/whatisana1a2a3ora4.msnw

    http://groups.msn.com/TheMarylandAR15ShootersSite/sightsopticsfaq.msnw

    http://www.xssights.com/faqs.html#faq4

    Take a look at the XS Sight systems "Precision Tactical Rear" aperture. It's a "Same Plane" sight. They sell this as a replacement for the standard A2 aperture because the latter will change your elevation when you flip it.

    http://www.xssights.com/store/tactical.html
     
    Last edited: Apr 12, 2008
  22. rangerruck

    rangerruck Member

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    I am going to sound stupid and chime in here, so I guess it may be our point of reference. When I joined the army, we still had the a1, and were transing to the a2. I can remember many, many times, that shooting instructors, mostly DI's, specifically told us that the larger app ring was for fast acquiring, and closer up shooting.
     
  23. Onmilo

    Onmilo Member

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    Correct, they were M16A1 rifles.
    The only experience I had with the M16A2 was a repair course that dealt with the installation and maintenance of the burst fire mechanism and the installation and removal of the A2 rear sight assembly.

    Every Qualification I did was 40 rounds from the foxhole supported position and the maximum range I am sure was 400 meters.
    I only remember firing from the prone position for the 25 meter zeroing and during the Combat Rifle Course, I cannot ever remember firing from the prone during the Standard Rifle Qualification. HTH
     
  24. cdbruster

    cdbruster Member

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    During my time in the USMC, I was instructed by PMI's, senior Marines and likewise passed down to junior Marines that the aparture (ring) with the larger inside diameter is for low light conditions and closer ranges. The aparture with the smaller ID is for brighter light and longer range engagements. There really is no cut and dry rule as to when you have to use one or the other. If you are taking a 75 yard shot and it is very bright outisde, it may be prudent to use the smaller aparture. The pros of each are. Larger Aparture: quicker sight picture and good for low light conditions. Smaller Aparture: more acurate sight picture and good for more intense light. I have never been told the center line of one aparture is higher or lower than the other therefore rendering different range BZO's. If that were true, what is the elevation know used for? Rhetorical Question, don't answer that bacause there is no elevation or aparture centerline difference from the larger to the smaller. What I want to know is what is the sight height difference between the A4 (M4 Carbine) and the A2, A3. It seems the A2, A3 have lower profile sights than the A4 (M4). Does anyone have any information?
     
  25. Tarvis

    Tarvis Member

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    Now, I am not an expert, nor in the military. That being said, here are my observations: It seems like the M16's operator manual would mention something about an elevation difference between the two apertures. I haven't read the operators manual, but it sounds like the large ring is meant for low light which doesn't have a whole lot to do with elevation. The civilian market doesn't know very much about military guns, mostly because they don't sell them. More importantly, the civilian market doesn't sell military guns. A guy at a gun show once told me that BUIS makes a good fold up iron sight. I thought about telling him it was an acronym for Back Up Iron Sight, but I figured he'd get it sooner or later.

    I'd say the best way to figure out if your rear sight has a different center for each aperture would be to get out your caliper and measure each hole.

    Another thought: it could be possible that the elevation between the two appears to change due to a different sight picture, caused by changing the sight alignment for each aperture.
     
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