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Barrel Threading (.308 Winchester)

Discussion in 'NFA Weapon Discussion' started by AMProducts, Nov 4, 2010.

  1. AMProducts

    AMProducts Maple Valley, WA Jerk, Ammo Manufacturer Silver Supporter

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    So I was planning on threading my barreltomorrow (Savage 10FP-LE) with the intention for now of mating a compensator. However, eventually I want to set it up to fit a gemtech or other .308 quick-detach suppressor.

    Everyone is willing to tell me it's a 5/8"-24TPI thread I need to cut, but how long should the cut be? It seems most people take the thread profile from AR-10s, does anyone know how long that is from the tip of the muzzle to the shoulder?

    Would appreciate any guidance on this. Thanks!
  2. novamind

    novamind Hillsboro Active Member

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    I would not cut it until you have the compensator in hand and, can verify the TPI and depth and length needs for it. Are you going to use a metal lathe to cut the treads?
  3. Ranb

    Ranb Belfair, WA Active Member

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    Here is a thread guide to give to your gun smith. http://www.silencertalk.com/AAC-thread-guide.pdf One of the 5/8-24 (.625-24) will be good. Which one depends on the style the silencer uses. You might want to contact Gemtech. I do not have an AR-10 barrel to measure for you though.

  4. Wallygator

    Wallygator Albany, OR Active Member

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    Did you get the threading done?

  5. Tornado-Technologies

    Tornado-Technologies Hillsboro Active Member

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    Threading length should be between 0.6" and 0.625", if you go longer than that you run the risk of bottoming out in the muzzle brake, in fact a lot of the muzzle brakes will bottom out less than 0.6" as they're designed to be used with a crush washer.
  6. Madwulf

    Madwulf Wenatchee Member

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    You guys are spot on again.
    I always did the threading to be done to fit the device being mounted.
    I've done a few dozen barrel threadings, and I always ask for the "thing" going on the barrel to be nearby to use as a measurement source. I use a micrometer depth gage to find the shoulder depth in the muzzle device and take a coupe thousandths off. That is : if the QD suppressor mount is 0.6255 in depth to it's insdie shoulder, I cut the threads to 0.620 in length on the barrel.
    When you thread on your device, it should snug down on the threads and be just at the verge of bottoming out.
    I also cut the threads to a very close and tight fit within the threaded device. I tried to keep a perfect fit between the barrel and the device. A tight fit meens less wobble.
    Remember to chuck-up the barrel with a bore centering guide as a alignment tool, not the outside diameter of the barrel.