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16" or 20" AR?

Discussion in 'Rifle Country' started by kennygarza, Feb 23, 2006.

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  1. kennygarza

    kennygarza Member

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    I'm looking into getting an AR-15, but I can't decide on which length to get it in. If I go the 16" route, it will have the collapsable stock on it. This will be mainly just my fun gun. Shots will be at 300 yds. max., usually around 100 yds. I'd like to hear from some of you that have either one, pros and cons. I like the idea of a handy carbine, but I also want something that I can reach on out there with from time to time.
    Any info would be greatly appreciated.
    KG
     
  2. Rem700SD

    Rem700SD Member

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    My vote is for the 16" bbl. It's much handier, lighter at the fore-end, and better as a fun gun. The downside is that it will be a little louder, and the velocity will be lower. I think the accuracy will be the same.
    My.02
    Dan
     
  3. ocabj

    ocabj Member

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    Whichever you get, make sure it's a 1 in 7" twist so you can maximize use of the heavier weight bullets, specifically the 75 and 77 gr offerings from Hornady, Nosler, and Sierra.
     
  4. 355sigfan

    355sigfan member

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    The 16 inch is my choice. The 20 inch gun is less manuverable in tight spaces. The 223 is not a long range round and is more at home in a carbine.

    I prefer the 1 in 7 twist but you can do fine with a 1 in 9. The heavy bullets are great but the 69 grain loads will work in a 1 in 9 and their heavy enough.
    Pat
     
  5. _N4Z_

    _N4Z_ Member

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    *

    I used 20" in the Army and for 300 yard or meter shots, it filled the bill nicely. To me 300 meters with iron sights IS long range.

    If your looking for a fun toy to impress yourself with at the range (out to 300m) go 20. If your wanting it for urban warfare, home defense, yada yada sis boom bah, go 16. Probly not much diff between the two but I prefer the longer barrel.
     
  6. Jacobus Rex

    Jacobus Rex Member

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    I went with the 16" on my AR for compactness reasons. Although, I use an A2 stock. I like the shorter front combined with the longer stock.

    I don't think that the 16" is a disadvantage at realistic ranges. Most of my shots are taken about 100 yards or less.

    For a varmit/target gun, I'd use the 20" or longer. Other than that, I'd stick with a 16"

    I went with 1 in 9 twist as the best overall and good for shooting cheap 55 grain stuff.
     
  7. engineer151515

    engineer151515 Member

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    Sold my 20". Have two 16".

    My $0.02.

    Get the 16" then buy a 20" upper later (if you still feel the need).
     
  8. MechAg94

    MechAg94 Member

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    I got a 20" Armalite. It seems plenty light and handy for me, at least compared to an M1A or my Vepr. My Dad has a 16" Colt sp1 and that is a handy gun. Yeah, I do think it depends on what you want it for. I like the 20" though.
     
  9. ArmedBear

    ArmedBear Member

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    I've been pondering the same thing. And I already have a stainless Ruger Ranch Rifle, which is a handy little thing and fine at 100 yards.

    I've been leaning towards 16" for the AR, though I'd like a straight heavy barrel, not an M4, since I have no plans to add a grenade launcher. I do see an accurate 20" in my future, though.

    But what about the buttstock? I suppose my wife will shoot it now and again, so adjustable could be nice. But is there any other reason to get an M4 or CAR stock? If so, which of those? (Note: I'm too cheap to get a SOPMOD).

    Do carbine stocks have FTF problems with 20" uppers? Or is that just an unconfirmed rumor?
     
  10. Bartholomew Roberts

    Bartholomew Roberts Moderator Emeritus

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    A 16" barrel is capable of wearing out targets at 300yds with no problem at all. The only real change the 20" gives you is a longer sight radius in the stock configurations of each rifle (though you can make a 16" rifle with the same radius as the 20") and about 100fps more velocity.

    20" barrels have no problems with collapsible stocks.
     
  11. georgeduz

    georgeduz Member

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    yes i think 300meter i about the limit you can see a human size target.i have a 20in barrel.but i just order a 16 in upper kit from olyimpic arms.i dont think there be much different.i,ll let you know when i get it to the range.they claim to have very good barrels so we will see how it compares to my colt target match 20in .
     
  12. Zach S

    Zach S Member

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    I prefer a 16" with a collapsable stock.
     
  13. rangerruck

    rangerruck Member

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    if you are not going for kill shots outside of 300 yds, then the 16 will be lighter, funner, more accurate, stiffer.
     
  14. ocabj

    ocabj Member

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    Better yet, get an 18".

    [​IMG]
     
  15. BillL223

    BillL223 Member

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    First AR was a BM 16" V-Match. 2nd was a 20" JP upper on a BM lower. Both were good however I rebarreled the 16" with a 20" cut down to 18". This seemed better. Sold that, got a new JP 18" upper on a BM lower. This combo of a 20" gas system on a 18" barrel is great.
     
  16. ArmedBear

    ArmedBear Member

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    That's my other question.

    Is one gas system more desirable than another?

    How reliable is the 16" with 20" like a Dissipator? Is a mid-length worth the trouble of having a non-standard foreend?
     
  17. ocabj

    ocabj Member

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    The two reasons why the midlength gas system caught on is because of the longer sight radius (compared to the original carbine length) and the claims that a midlength system is gentler on the upper receiver, bolt, and buffer assembly.

    As far as the reliability of having a full length gas system on a 16" barrel, it will function just fine.
     
  18. MatthewVanitas

    MatthewVanitas Member

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    A Dissipator will be no different in reliability from any other AR-15 carbine. The Dissipator has the exact same placement of the functioning gas block as on a carbine (which ends up being under the handguards). The front sight base does not serve any gas-bearing function, it's just there to hold the front sight out in the 20" position.

    If you get a Dissipator, strongly consider getting a M4-profile or fluted barrel. Everyone with an HBAR Dissy says that it's muzzle-heavy, but I got the M4-profile Dissy barrel from Bushmaster and it balances just great.

    If you like the fixed stock, but want a little bit shorter than the A2, consider getting an A1-length stock. Cavalry Arms makes them new-prouction for a good price. I just bought a few of them, very happy with the size, and quality is good though buttplate is not mil-spec. PM me if anyone wants one of my spare A1 stocks for cheap.

    Ditto what everyone has said thus far IRT 20" vs. 16". Though I somewhat wish that I'd bought one of those 20" Colt M16A1 uppers for the retro-coolness.

    -MV
     
  19. Rob1035

    Rob1035 Member

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    Not to disagree, but how will a shorter barrel and sight radius be more accurate?
     
  20. cgv69

    cgv69 Member

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    As with most things, it depends on what you are going to be doing with it. In your case, for your purpose, it doesn't really matter. Either will suit your purpose just fine. I would just get the one that floats your boat the most. Before you make up your mind, here's some stuff you should know...

    A longer barrel does not mean better accuracy. Just more velocity. That's helpful if you are shooting at live targets but for punching paper, it doesn't matter.

    In the AR platform, a 20" barrel does buy you a few advantages. The first one only matters if you will be using the iron sights. If you going to use the iron sights, the longer sight radius of the 20" barrel will help, especially at 200-300 yds.

    The other is the gas system. A 20" barrel uses a "rifle" length gas system. A 16" barrel generally uses a "carbine" gas system. The short version of all this is the rifle gas system will have a little less felt recoil and they are generally a tad bit more reliable.

    A happy middle ground is a 16" barrel with a "Mid-Length" gas system. With a mid-length gas system, the gas port (and hence FSB) is 2" further out towards the end of the barrel. This gives you the compactness of a 16" carbine but recoil and site radius closer to a rifle length barrel.

    One last thought. Collapsible stocks are "cool", especially because they were so "evil" for 10 years. They can be useful if you wear body armor or need a very short LOP for some reason but that said, a fixed stock, especially a A1 length, is so much more enjoyable to shoot. Its just really hard to get a good check weld on a typical collapsible stock and even if you do, chance are it won't be comfortable.

    In short, I think a 20" rifle with a fixed stock will provide you with the most enjoyment at the range but if a 16" carbine is what you want, then go with that. The best rifle in the world may not be any fun if its not what you want. As long as it's a quality built carbine, it will serve you and your purposes just fine.
     
  21. Bartholomew Roberts

    Bartholomew Roberts Moderator Emeritus

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    The bolt and cycle of the AR15 were designed to work with the 20" rifle. On a 20" rifle, the gas port pressure is around 12-15k psi and located about 13" down the barrel. In a carbine, the gas port pressure is about 28-30k and is located about 9" down the barrel. This means that the carbine cycles harder, faster and is trying to extract the fired case while pressures are higher than they are in the rifle.

    A midlength drops port pressure to around 18-21k and moves the distance out another 2". These are pretty well understood facts. Just shooting a carbine and a midlength side by side you can tell the difference in the smoother recoil of the midlength. From a practical aspect, this should mean that lifespan and parts breakage on a midlength should be more rifle-like than carbine-like. Just watch the training video of the XM16E1 and you should be able to understand why the amount of gas pressure and the distance it travels is relevant to the functioning of the rifle.

    Also, while a midlength isn't exactly standard there are literally dozens of firms making midlength furniture, so parts shouldn't be an issue at all.

    Based on what I have read, 16" barrels with rifle-length gas systems suffer from some of the same short dwell time and reliability issues that plague the 10.5" shorties. With so little barrel past the gas port, the bullet leaves the barrel and the pressure drops before the gun can get enough gas to cycle reliably. If you go this route, you need somebody who knows how to open up the gas port to the correct diameter and a muzzle device that creates some backpressure isn't a bad idea either. However, a better response is either a midlength or carbine gas system under the handguards.

    17" is about the shortest you can go and use a rifle-length gas system without adversely affecting reliability.
     
  22. 355sigfan

    355sigfan member

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    Actually the little guns have a larger gas port and have enough gas. The problem is that there is not enough dwell time before the pressure drops and the bolt carrier starts to move back. The case is still swelled and this casues extraction difficutlities with the little guns. Hence the reason for the pig tail. It does not add gas but rather increases the dwell time and allows pressures to drop.
    Pat
     
  23. Bartholomew Roberts

    Bartholomew Roberts Moderator Emeritus

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    It is kind of a chicken or the egg deal. You can't use a normal carbine-size gas port on a shorty even though the gas port is in the same location because the bullet will exit the barrel before you get enough gas.

    So to fix that, you open the gas port so that the gun gets enough gas to cycle before the bullet leaves the barrel; but in a 10.5" barrel this means the gun is trying to cycle while pressures are still too high. So now you throw in patchwork fixes like pigtails to delay the time it takes for the gas to hit the carrier or heavy buffers to slow the cycle.

    I think the best fixes for direct gas guns are solutions like the Krink flashhider or suppressors that create enough backpressure that you can run the shorty with a smaller gas port; but even then an extra inch or two of barrel can be helpful to reliability.
     
  24. 355sigfan

    355sigfan member

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    I will agree that the shortguns are far more difficult to keep running reliably. I would like to see how the new gas piston guns do with short barrels.
    Pat
     
  25. kennygarza

    kennygarza Member

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    Thanks for the input, guys. I will probably be going with the mid-length Rock River... unless someone can convince me otherwise.
    KG
     
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