Barrel Length vs. Gas System Options

Discussion in 'AR-15 Discussion' started by diggsbakes, Jan 15, 2011.

  1. diggsbakes

    diggsbakes New Member

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    So, this really wouldn't have worked as a poll, nor did I want it to be one. I've really been enjoying this section lately as there's been some good content backed up by experience.

    To the Topic:

    On a Practical Level. . .

    How do YOU determine what length gas system YOU will use on your (X") barreled upper? Why?

    I know the basic "Normal" or "ideal" set ups that all have close to the same dwell time:

    14.5" = carbine length
    16" = mid length
    20" = rifle length

    OK, that's a good gauge, but I kinda like the way my 14.5" middy shoots. What about an 18" barrel? Mid or rifle?

    Let's hear it! :)
     
  2. Quentin

    Quentin New Member

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    As you said midlength works very well for 14.5 to 16". There is some overlap since you can adjust timing, dwell and pulse intensity with many factors such as gas port size, position and bolt carrier/buffer reciprocating mass. Each manufacturer does it different and you can change some of the factors yourself.

    KAC has an intermediate length gas system that works well for 18" or even 16". Rifle does well on 18" too. Mid might work but I'd go with a longer gas system.
     
    Last edited: Jan 15, 2011

  3. mjkeat

    mjkeat New Member

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    I cant really add anything to what Quentin said. In my eyes 14.5" midlength is ideal.
     
  4. Quentin

    Quentin New Member

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    I agree with mjkeat that a 14.5" midlength is ideal. But in the real world with legalities and for flexibility I went with a 16" midlength for my first build and did it again with my second (but this time with a lightweight barrel profile). I just don't want a pinned/welded muzzle device and when it comes down to it the actual differnece in length is barely an inch.
     
  5. M14sRock

    M14sRock Active Member

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    MJ and Q got it. The mid-length and full length have a smoother recoil impulse.
     
  6. diggsbakes

    diggsbakes New Member

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    Well I guess if 14.5" mid-length is ideal, which I can't argue with after shooting my mid-length BCM upper today. I couldn't imagine anything smoother.

    Then that would mean that rifle length would be sweetest for an 18" barreled upper. . . ?

    I'll post up a target from 200 yds that the BCM put out using Silver Bear ammo in range reports.
     
  7. JonM

    JonM Moderator

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    yup you got it.
     
  8. mjkeat

    mjkeat New Member

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    Id like to try a 16"-16.5" w/ rifle length gas system out of curiosity.
     
  9. diggsbakes

    diggsbakes New Member

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    Yeah that was truly rocket science. . . Does anyone have experience with an 18" barrel/rifle length AR set up?
     
  10. Quentin

    Quentin New Member

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    That would be nice MJ. Or intermediate length but then there's so little selection for furniture/rails. Yeah rifle...

    ETA... didn't see your post Diggs... no 18" here.
     
    Last edited: Jan 15, 2011
  11. JonM

    JonM Moderator

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    No need to get snarky, you prolly won't find a rifle length gastube on a short barrel there won't be much if any room for the gas block. You would need to have a custom barrel made.

    Midlength would work very well. It is just as smooth as full. I've fired a few.
     
  12. mjkeat

    mjkeat New Member

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    I had a 18" WOA SPR profile that was rifle length. It shot nice.

    [​IMG]

    [​IMG]
    55gr.
     
  13. diggsbakes

    diggsbakes New Member

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    Now that's what I'm talking about! I'm looking into this one:

    White Oak Armament SPECIAL PURPOSE RIFLE (SPR) Match Barrel

    This SPR .223mm barrel is the product of the Army's Squad Designated Marksman Rifle Development Program, which was assigned the task of improving the accuracy of the standard issue rifle against targets out to 600 meters. This would allow the valued marksman or sniper the ability to stay concealed within the squad by carrying a weapon that looked similar to the rest. It was found that by carrying a dissimilar rifle, he had become an easily recognizable high-priority target. We offer this barrel to the tactical user or casual shooter interested in the ability hit distant targets with issued or mag length ammunition.

    · 18 inch 1-7 twist Match Grade Stainless Steel barrel
    · Chambered to give excellent performance and reliability with a wide variety of ammo
    · Light weight contour ( total weight of 41 ounces )
    · 1/2x28 threaded muzzle to accept standard .223 flash hider or muzzle brake
    · Choice of Rifle or Mid-Length gas system
    · Choice of Standard or M-4 Ramped Barrel extensions


    5sprr SPR Barrel w/ Rifle Length Gas $265.00
    5sprm SPR Barrel w/ Mid-Length Gas $265.0
     

    Attached Files:

  14. Dillinger

    Dillinger New Member

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    We have been recommending White Oak for a couple of years now for accurate, varmint and "sniper support" style AR's. They are a great barrel, a very good company to deal with and their prices won't put you in the bread line.

    I can recommend them without question for anyone who is building, or wanting to build, an accurate AR and can spend a few extra dollars on a really good barrel to complete the platform before optics.

    JD
     
  15. Dillinger

    Dillinger New Member

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    I got an 18" Upper from Larue and slapped it on a lower I built and it shoots dimes all day long with factory ammo. Than again, it wasn't cheap. :p

    I'd post some gun pr0n, but I know how Lon feels about Larue and I don't want him drooling and ruining another keyboard. ;)

    JD
     
  16. M14sRock

    M14sRock Active Member

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    My shooting partner's JP is a 16" with a mid length gas tube. It is a dream to use.
     
  17. diggsbakes

    diggsbakes New Member

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    Yeah, I'm really glad ya'll turn folks to White Oak. After first hearing of them here, I've spoke to some of the owners of the range and shop I frequent and they say the same. Shouldn't be more than a couple weeks before I have a range report.

    The only thing is I only have one decent scope that's not in use. A Nikon Monarch 2.5-10 x 44mm. It's great and all, but I don't know if it'll be AR appropriate, unless I have an open style red-dot up top or something of the like? Of course I'm gonna try it out. :)
     
  18. mjkeat

    mjkeat New Member

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    Middys are nice.

    Whats wrong w/ that? I battled the, "must have BUIS and an offset RD," then came to the realization that the rifle is for range use so WTH
     
  19. diggsbakes

    diggsbakes New Member

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    'Cause I've battled it as well and determined that I DO like BUIS and want them on all rifles w/ optics. AR or not.
     
  20. mjkeat

    mjkeat New Member

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    Then go w/ a 1.93 Larue mount. Theres another version but I cant think of the name at this time. I think its a 1.75 or something similar. The 1.93 will give you plenty of clearance but I think it changes your cheek weld a little. The next size shorter is a tight squeeze for gen 1 MBUS. The gen 2 and other brands should be fine.

    I'm going to start saving for either a 1-4 or ? for the .300 blk on order. The size of the 1-4 is ideal but not sure its enough for hunting. Ive never hunted anything but birds so I'm clueless.