best handguard length for adj mid length gas system

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  • Dave

    Ultimate Member
    Jul 10, 2008
    4,296
    Gamber, Marylanistan
    Hey all,

    need some help with my next build. Right now I'm looking at a 6.8 upper from https://www.blackstonearms.com/category-s/100.htm With a 16" barrel and adjustable gas block, what length rail should I go with? Choices are 11, 13.7, and 15". Going to be mostly a bench rest and hunting gun, but also has to support a suppressor. 11" would keep the gas block accessible, but I would prefer a longer rail. I asked them if they can source the 12" m-lok rail, as I think that would be a happy compromise. Or should I just get the 13.7 (designed for 14.5" barrel I know) and find a longer allen wrench? pictures of similar builds would be greatly appreciated!

    thanks,
    Dave
     

    Racer Doug14

    Thread killer
    MDS Supporter
    Patriot Picket
    Feb 22, 2013
    8,003
    Millers Maryland
    I'd say 11". Mid-lenght GB on my two ARs is still kinda far back, I have 13" BCM and Noveske hand guards. Depending on how easy/hard it is to adjust 13" could be to difficult.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,816
    Liking the 11" idea more and more. Less weight up front the better too when can is attached.

    I wouldn't go beyond 11"

    I can't read so good, I didn't see which upper you were looking at or what gas length. I prefer 10.5", whether it's an SBR or full length rifle, but the brand and type I use doesn't make an 11" so...
     

    Racer Doug14

    Thread killer
    MDS Supporter
    Patriot Picket
    Feb 22, 2013
    8,003
    Millers Maryland
    Oh, the pic would help. Duh.
     

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    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,816
    Mid length gas block

    You could go longer, depending on the GB. If it's an allen key type, you can get any length driver to reach it. If it is a lever or knob type(usually having only 3 settings), it will probably need to be exposed to digital manipulation. It will need to be exposed.
     

    Dave

    Ultimate Member
    Jul 10, 2008
    4,296
    Gamber, Marylanistan
    You could go longer, depending on the GB. If it's an allen key type, you can get any length driver to reach it. If it is a lever or knob type(usually having only 3 settings), it will probably need to be exposed to digital manipulation. It will need to be exposed.

    good point. It's allen, but wanted a lever. If they can source a lever block, I'll go 11, if not, I'll probably stick with 12 as a happy medium
     

    alucard0822

    For great Justice
    Oct 29, 2007
    17,643
    PA
    I prefer as much handguard as I can get, usually within 1-2" of the barrel length out to around a 15" guard, lets you grab the rifle far out front for better handling, and easier to use random things for support. For suppressor use, you could go flush or longer than the barrel depending on adapter, still probably 1-2" shorter if the adapter is a brake. Most rails only add around 1oz for 2-4" of rail length, so there really isn't much of a weight/balance penalty, and some lightweight designs have large enough ports that you can use a ball-end driver from an angle to the side to adjust the block instead of a really long driver from the muzzle end. I can adjust all of mine like this, only need the long driver to close/open them fully if they get sticky with carbon, otherwise I can find a spot to adjust them through the handguard vents. These are some of my 16-18" rifles I use SLR or Superlative gas blocks with detent/single screw(FM9 is 9mm blowback), 18" M5(308) with 15" Aero R1, 18" mega with 16" MML, 16" Vseven with 15.5" Odinworks O2, 16" FM9(9mm) 15" FM rail.

    20190619_092247.jpg
     
    Last edited:

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,816
    Would it be possible to cut a "notch" out of the longer HG to adjust the GB?

    Conceivably for an SLR, but not the most practical method. Knob types, I would say no. Many require pushing a button and turning a knob simultaneously. As carbon builds up, they can tend to get a little stubborn.
     

    Dave

    Ultimate Member
    Jul 10, 2008
    4,296
    Gamber, Marylanistan
    I'm just gonna stick with a regular allen adjustable block. what the builder recommended as well. Still can't decide on hand guard lol. One thing is certain: I'll wish I had gone with whatever option I don't get :p Looking like 12" is gonna be the compromise since I can't make up my mind.
     

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