15 inch barrel, with rifle gas! almost rifle velocity, and i runs great

Discussion in 'AR-15 Discussion' started by Middleofthemiddle, Jul 31, 2012.

  1. Quentin

    Quentin New Member

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    Does that thing cycle with Wolf? Heck, does it cycle with anything? :D
     

  2. Middleofthemiddle

    Middleofthemiddle New Member

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    I won't shoot wolf but I shoots pmc .223 and and all the 5.56 I have put through it. It just took some fine tuning, but it runs smooth and very clean. Its getting 3025 fps with federal 5.56. I had this idea and I was sure I can make it work
     
  3. Quentin

    Quentin New Member

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    Well it looks great!
     
  4. Middleofthemiddle

    Middleofthemiddle New Member

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    Thanks! It has a 20" rra hbar that i cut to 15" and permed the flash hider. I also cut a 11 degree crown.this thing is also sub moa
     
  5. SSGN_Doc

    SSGN_Doc Well-Known Member

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    What was your idea?

    The Dissipator ahs been around for a while. 16" barrel with rifle gas system and some versions with carbine systems and rifle length hand guards. Short barrel with long sight radius and more heat shielding to "Dissipate" the heat was the original marketing on them. Bushmaster and DPMS made versions and had a law suit over who could use the name Dissipator. The gas sytem shouldn't have much to do with the velocity. Right around 3000-3100 FPS is about normal for a 55gr load. A 20" barrel would get it up to about 3250-3300 FPS.

    Some folks ahve had cycling issues with rifle length gas systems on carbine barrels in really cold weather, but that is about the only negative I have seen along with some ammo sensitivity for lower powered rounds. This can sometimes be corrected with a lighter buffer or opening up the gas port a bit to get more gas into the system to compensate for the reduced dwell time that results form having the port so close to the muzzle.

    Enjoy the set up, they are really sweet to shoot. I've been a "Dissy" fan for a long time
     
  6. SSGN_Doc

    SSGN_Doc Well-Known Member

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    Oh, Now I see from your most recent post that you cut the barrel to 15" and perm attached the FH. That would indeed be a bit different than a 16" Dissy.
     
  7. Middleofthemiddle

    Middleofthemiddle New Member

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    The dissy barrels had middy set up, just a rifle sight radius. And with the gas not dumping the pressure untill the end of the barrel not the middle or the beginning. It has more time for the gas to expand without losing pressure. So it retains more velocity. 2900 to 3000 through the crony.
     
  8. powell0892

    powell0892 New Member

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    I think the rail should be a little longer :D
     
  9. Middleofthemiddle

    Middleofthemiddle New Member

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    Haha, its going to be awesome when I have a can to put on it.
     
  10. SSGN_Doc

    SSGN_Doc Well-Known Member

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    Original Dissys had a carbine system as Bushmaster made them. DPMS used rifle length gas systems. I run one with a carbine system and get pretty much the same velocity with Federal XM193 that you are getting. I have shot them with the rifle length system, and they do cycle much more gently, which makes them more pleasant to shoot and very smooth feeling.

    Yours looks really nice. Having the muzzle an inch closer to the handguard makes it look much cleaner.

    I really like RRA s barrels and have found them to be very accurate. You got a good barrel there to work with.

    [​IMG]
     
  11. Middleofthemiddle

    Middleofthemiddle New Member

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    When I shot it at the range at my work it was 58 degrees. The a/c was blasting, and I was getting 3000 fps. Now I'm exited to see what velocity I get outside where its been around 80. That should make my numbers a bit better