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Thread: DD RIS II and Intermediate Length Gas System

  1. #1
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    DD RIS II and Intermediate Length Gas System

    I’ve searched around and haven’t found anything definite.

    I’m wondering if the DD RIS II, the 12.25” model will fit over a barrel with an intermediate length gas system.

    I was going back and forth between the Lite 12.0 (12.65") and the RIS II. I like the profile better of the RIS II. The Lite is open at the muzzle end, while the RIS II is partially enclosed. I’m worried this little section which serves to close off the end of the RIS II will make contact with the gas block (Novekse/Vltor low-profile).

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    I use the Mk18 RIS IIon a DD CHF 14.5" mid-length... Other than about a half inch of projection of the low profile gas block, it fits fine. I think the M4 RIS II will work, and cover the gas block completely. You just need to use a low profile GB...

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    Do youmeanthe KAC intermediate gas system?
    Im looking at photos of a middy with a RIS II M4 and a 16 KAC sr15 and it looks Like you should be just fine. It will be close but it should settle just behind the RIS II's chin.
    Worst case scenario, again, purely from photo comparisons, You'll have to dremel the GB's front a bit. Not hard to do and it doesnt take much to clear the chin. I have the same set up as Tom but with a 16 middy and a standard GB which I had to dremel at the rear to clear the rail. Took me 15 minutes max, 10 of which was mostly due to my OCD's serious need to make things even.

  4. #4
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    What pic are you looking at?

    I am talking about the intermediate length gas system, longer than a mid-length, shorter than a rifle.

    Its a MSTN/Noveske barrel, but yes, very close if not the same as the KAC gas system.

    I was just wondering about clearing the chin (I like your description of it) of the RIS II.

    The front of my gas block has a slight angle to it, looks just like the stainless one in the third pic in this thread from TOS...

    http://www.ar15.com/forums/topic.htm...=521661&page=1
    Last edited by bp7178; 03-07-11 at 00:12.

  5. #5
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    I wasn't aware of the length of the intermediate gas system... but, if it's any further forward than a mid-length then you might run afoul of the rails forward opening or in the case of the RIS, the key-hole. My experience is with a DD low-pro pinned gas block which is fairly minimal in it's footprint on the barrel, and it fits well through the key-hole of the RIS II. I couldn't tell you if the other types of gas blocks would work the same. As the others have stated, you may have to mod the gas block to clear the front opening of the RIS because it is smaller.

  6. #6
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    the gas port on a noveske intermediate is at 11.5" from the face of the receiver. so a handguard that goes out to 12.0" will cover about half of a noveske/vltor style gas block, the other half will stick out. if it's pinned, it matters not.

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    There was a pic on militarymorons of a intermediate gas system with one of the 12.0 Lite rails. It looked as if the gas block was about 1/4-1/2" from the end of the handguard.

    Where this gets fuzzy is that there are different specs listed of the rails depending on the source. IIRC, the 12.0 Lite is actually 12.65" and the RIS II is 12.25".

    I'm thinking if the RIS II fits, it's going to be very close. I had ordered one from Brownells. I may have to call them in the morning and change it to a Lite.

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    Just in case anyone else decides to try this combo out, it DOES fit. Plenty of clearence between the gas block and rail system. I was worried that the lower lip of the rail would make contact with the gas block. There is actually a decent gap there, where the gas block could pass completley through the opening.

    Funny thing is the manual lists the rail as 12.57". Mine was date coded Aug 2010.

    Very happy with the rail.




    Last edited by bp7178; 03-10-11 at 12:09.

  9. #9
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    Quote Originally Posted by bp7178 View Post
    Just in case anyone else decides to try this combo out, it DOES fit. Plenty of clearence between the gas block and rail system. I was worried that the lower lip of the rail would make contact with the gas block. There is actually a decent gap there, where the gas block could pass completley through the opening.

    Funny thing is the manual lists the rail as 12.57". Mine was date coded Aug 2010.

    Very happy with the rail.




    Thinking about getting one... is it worth the extra money and weight over the light rail?
    Taken from a random Sniper's Hide Post
    It's really hard to judge by the size, but that [critter] looks to be in the class of "Big Mother ****er" and perhaps the family of "Stay the **** Back"

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    Quote Originally Posted by Find ManBearPig! View Post
    Thinking about getting one... is it worth the extra money and weight over the light rail?
    To me, the best thing about the RIS II over the Lite Rail is the tucked up 6 o'clock rail. They also have anti-rotation stops and removable lower rails if those things are important to you.

    KAC RIS/RAS
    Larue Tactical
    DD RIS II
    ^^^These are the only rails that have bottom rails tucked up close to the barrel. I like 'em.

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