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Thread: 12.5 vs. 14.5

  1. #1
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    12.5 vs. 14.5

    Needing some help before I purchase some parts.

    Looking to complete a SBR project, the lower is already Form 1

    I am having a hard time deciding between doing a 12.5 or 14.5 5.56

    I have listed my pro's and con's below. the main thing that appeals to me about the 14.5 is the mid-length gas, but I also realize that the length is so close to my existing 16inch gun, I'm having a hard time justifying it.

    What is important to me: Accuracy, smooth shooting gun, good platform for suppressor host, I already own 16 and 18inch 5.56's with 1-6's, plus 8inch 300blk. I want an 11inch rail, thus the 12.5 over 11.5 length, I find 10.5's annoying to shoot, and want to get velocity, I would want to be able to shoot out to 400yd with this gun, maybe further, primarily run a RDS but could put 1-6 but mainly I will shoot it 100yd and in.

    This gun will wear either the Silencer Omega or Specwar-K suppressor, just guessing 75% of the time. I will run an adj gas block and plan on tuning the gun for the can so its not over-gassed. I'm leaning towards just direct threading the omega to the gun with the 5.56 end cap unless I can feel a difference in recoil with the omega brake.

    12.5
    Pros
    Shorter and handier
    improved balance with suppressor

    cons
    carbine gas
    harsher recoil
    increased muzzle blast


    14.5
    pros
    longer rail
    mid-length gas
    should be smoother, softer shooting
    greater velocity

    cons
    longer
    front heavy feel with suppressor
    so close in length to current 16 inch gun

  2. #2
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    A properly sized gas port or a properly installed adjustable gas block will yield no differences between 14.5 mid or 12.5 carbine, as far as felt recoil is concerned in my experience. It's not worth the $200 to build a 14.5 SBR. I'd personally opt for the 12.5.

  3. #3
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    I'd definitely vote 12.5". I think the only real purpose of a 14.5" is to pin the muzzle device and skip the $200 stamp.

  4. #4
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    Quote Originally Posted by BigWaylon View Post
    I'd definitely vote 12.5". I think the only real purpose of a 14.5" is to pin the muzzle device and skip the $200 stamp.

    Yep. Getting a stamp for a 14.5 is a waste of money. If you're gonna have a sbr, have a sbr.

  5. #5
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    Going to agree with the others here. The longest I would personally go if I was going to SBR an AR would be 12.5. The only reason I could see going to a 14.5 AR would be if you are wanting to clone the M4 you carried overseas and wanted it for sentimental value, otherwise 14.5 pinned and welded, or just 16 inch barrel makes more sense otherwise over the tax stamp.
    "I don't collect guns anymore, I stockpile weapons for ****ing war." Chuck P.

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  6. #6
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    I have a 12.5" that is absolutely amazing, and it wears a Saker-K 100% of the time. By far my favorite gun. DD CHF 12.5" barrel, Colt upper/BCG, Noveske 11" NSR hand guard.

    --Nick
    Owner, Reptilia & Side Project, LLC

  7. #7
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    I wouldn't bother with a 14.5" SBR. I don't think it's worth the money. My initial reaction when reading your post was to recommend 11.5" but you specifically stated you don't want that and why. Therefore I'm with everyone else here and feel the 12.5" is the best way to go. As far as a 12.5" with carbine gas system vs. a 14.5" with mid-length gas system goes, this is a non-issue. What's important is that you have the proper size gas port for the barrel length and gas system combination. This is even more of a non-issue since you're going to be running an adjustable gas block (as Leonidas24 talks about above).
    Steve

  8. #8
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    I would do the 12.5 also. I sold my 14.5 mid because it didn't fill a role that my 11.5 or 18" gun couldn't cover.

  9. #9
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    I feel that the 12.5 5.56 AR is the best all around system. I like 14.5 barrels but to choose I will go 12.5 any day. 12.5 is the shortest barrel that you can go and still get proper stabilizing of the heavy 5.56 rounds. I have had no issues with a 12.5 out to 400 plus meters with MK262.

    I have a 12.5 Noveske Lite CHF and it is my go to gun. I shoot it suppressed most of the time with an AAC Mini4. It runs great and I have had no issues with it.
    Info here: https://www.m4carbine.net/showthread...2-5-GP-Carbine




    I am also in the process of putting together a new 12.5 with a Rainier Arms Stainless Steel Mid length gas system barrel.
    Info Here: http://www.rainierarms.com/rainier-a...id-barrel-12-5

    Here is what I have so far. I am setting it up for more of a precision gun.

    In no way do I make any money from anyone related to the firearms industry.


    "I have never heard anyone say after a firefight that I wish that I had not taken so much ammo.", ME

    "Texas can make it without the United States, but the United States can't make it without Texas !", General Sam Houston

  10. #10
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    Different barrel lengths with the different gas lengths all have different attributes. There can be many more choices at hand than what the OP selected as far as selections for either. You can make a carbine gas 12.5" that never sees a can run well up to a mid gas suppressor only combo. The same goes for the 14.5" barrel, from carbine length to intermediate depending on how it's used. Remember that regular carbine length, carbine + 1", mid gas, KAC length, intermediate lengths can be used in them, barrel length permitting. Dedicated porting is a personal preference over adjustable gas blocks. A rifle like (A5H2) action system increases reliability, as other things. Another thing to consider is how the silencer effects function, as far as cyclic rate changes through the gas tube, and blowback through the barrel. Each is independent and changes with every combo.
    Just my 2 cents for this.
    Last edited by tom12.7; 04-29-15 at 21:09.

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