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Thread: So, if you want a rifle length gas system with a carbine buffer tube...

  1. #11
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    Unfortunately, there are just way too many important, but completely minute variables in fine-tuning the AR platform. Fortunately, there aren't too many ways to adjust it, at the user level (and not too many more beyond), so give it a go and see how she's runs is usually a great answer to these questions.

    If it was me, I'd put an H3 in there and try it with the Wolff spring with some anemic .223. If it short-strokes, swap the Wolff for a regular spring, and try again.

  2. #12
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    The gas system length is only a part of the answer.

    The gas port size is one other HUGE factor.

    The combination of those two things and the ammo determine how much gas drive the upper will produce.

    Good advice for 20" rifle gas uppers that were originally ported to use rifle buffers, is to start with a buffer around the same weight.

    That means an H3 or H2 CAR buffer.

    It's not surprising the standard A5 is also very close to the same weight.
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 12.5" MRC, 11.5" CQB, 9" PDW
    BRT EZTUNE Preset Gas Tubes - CAR and MID
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
    BRT MicroPin Gas Blocks - .750" & .625"
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports

  3. #13
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    Quote Originally Posted by Clint View Post
    The gas system length is only a part of the answer.

    The gas port size is one other HUGE factor.

    The combination of those two things and the ammo determine how much gas drive the upper will produce.

    Good advice for 20" rifle gas uppers that were originally ported to use rifle buffers, is to start with a buffer around the same weight.

    That means an H3 or H2 CAR buffer.

    It's not surprising the standard A5 is also very close to the same weight.
    I'm about to build a 18 inch rifle gas system and been doing a great deal of searching for a buffer and spring to get me in the "ball park" of what I want which is a light shooting "combat" rifle. I say combat because it is going to be a MK12 type rifle but with a twist.

  4. #14
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    I would not recommend to use this on duty rifles, but JP SCS-15 self contained recoil assembly is exactly same for rifle and carbine buffer tubes (to use in rifle tubes drop in included polymer spacer first). I understand that is was designed with rifle length gas system in mind. It is competition part, it costs fortune, but always an option.
    Montrala

    I'm sponsored competition shooter representing Heckler&Koch, Kahles, Hornady and Typhoon Defence brands in Poland, so I can be biased

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  5. #15
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    As I mentioned before. Assuming you have a rifle with a .093 gas port I would use an H3 buffer and blue Springco spring. It will run just fine.



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  6. #16
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    Quote Originally Posted by montrala View Post
    I would not recommend to use this on duty rifles, but JP SCS-15 self contained recoil assembly is exactly same for rifle and carbine buffer tubes (to use in rifle tubes drop in included polymer spacer first). I understand that is was designed with rifle length gas system in mind. It is competition part, it costs fortune, but always an option.
    Did I miss the new trend of putting experimental potentially self disassembling parts into fighting rifles? So can we please stop recommending race gun parts in fighting guns, we already went over this in the low mass carrier thread.

  7. #17
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    Quote Originally Posted by vicious_cb View Post
    Did I miss the new trend of putting experimental potentially self disassembling parts into fighting rifles? So can we please stop recommending race gun parts in fighting guns, we already went over this in the low mass carrier thread.
    You just missed "I would not recommend to use it on duty rifles".

    OP did not mention that it is duty/combat/HD rifle. There are people here who use their rifles for other things than combat.
    Montrala

    I'm sponsored competition shooter representing Heckler&Koch, Kahles, Hornady and Typhoon Defence brands in Poland, so I can be biased

    http://montrala.blogspot.com

  8. #18
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    Quote Originally Posted by Iraqgunz View Post
    As I mentioned before. Assuming you have a rifle with a .093 gas port I would use an H3 buffer and blue Springco spring. It will run just fine.

    Actually, you originally mentioned a green Sprinco spring. See above.

    The gas port is .085".
    11C2P '83-'87
    Airborne Infantry

  9. #19
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    So you have a 20" barrel with a small .085" gas port.

    What brand is it?

    That port size should be very soft shooting, like a very popular 14.5" mid length.

    I'd try something like an H buffer and standard spring to start.

    Quote Originally Posted by ABNAK View Post
    Yeah, it's a 20" barrel.

    Quote Originally Posted by ABNAK View Post

    The gas port is .085".
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 12.5" MRC, 11.5" CQB, 9" PDW
    BRT EZTUNE Preset Gas Tubes - CAR and MID
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
    BRT MicroPin Gas Blocks - .750" & .625"
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports

  10. #20
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    Quote Originally Posted by Clint View Post
    So you have a 20" barrel with a small .085" gas port.

    What brand is it?

    That port size should be very soft shooting, like a very popular 14.5" mid length.

    I'd try something like an H buffer and standard spring to start.
    Don't know. Bought it from McKay Enterprises. It is marked as follows: C MP B

    1:7 twist (I checked it myself), chrome lined, A1 profile.
    11C2P '83-'87
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