Adjustable gas block for SBR?

Discussion in 'NFA Weapon Discussion' started by Modeler, Dec 27, 2011.

  1. Modeler

    Modeler
    Molalla, Oregon
    Soccer Fan

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    Hi all,

    Considering how I want to build my SBR once I get the tax stamp in-hand. My SOT Dealer says that SBR's can be finicky with ammo sometimes, and that a larger gas port may be needed. I was thinking of building the upper with an adjustable gas block from JP Enterprises. I looked at the switchblock from Noveske, but they don't offer one with a front-sight option.

    What do you think? Is it necessary? Preferable? Waste of money?

    JP Rifles

    Greg
     
  2. JohnnyCauc

    JohnnyCauc
    Portland, OR
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    That depends on how "S" you're building your SBR.
    Mine is 10.3", with a gas port of 0.07 inch and I've never experienced anything regarding "finicky" ammo. I think as long as you keep the gas port size in mind when opting for barrel length. I ran it with a standard buffer weight for the first few years with thousands of rounds downrange with no problem (despite reading that a heavier buffer is used, most notably with full auto). All of this is 5.56, if that needs to be mentioned. Once I built my 9mm SBR upper for the same receiver, I started leaving my RRA 9mm buffer (5.6oz) in. Runs just fine with that as well.
     
  3. Modeler

    Modeler
    Molalla, Oregon
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    Primary upper will be 10.5", I'd like the ability to adjust for different loads (I do some handloading) and shut it down altogether for single-shots with the planned suppressor. If I'm gonna build it I might as well go all-out, right?

    Greg
     
  4. nrc

    nrc
    Oregon
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    I ran an adj block on my first 300/221, but don't use them anymore. A better investment would be a variety of buffer weights. Once your stamp clears, you'll want to add other lengths or calibers :) in any case.

    I've never had to change a gas port either - maybe I'm just lucky. Good luck waiting for your stamp!

    Nate
     
  5. Modeler

    Modeler
    Molalla, Oregon
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    One more question; call me old-fashioned, but I like the look of an A2 gas block. If I went with an A2 front sight will it interfere with optics I plan to add later?

    Greg
     
  6. nrc

    nrc
    Oregon
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    Lots of folks run scopes with a2 front sights... its not a big deal. You can sometimes see a 'ghosting' of the sight assembly through the scope but you can tune it out mentally easily enough.

    Oddly, the higher power scopes seem to have less of this effect than lower ones.
     

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