Want to convert a HA 5.56 to 6.5 Grendel

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  • va_connoisseur
    Warrior
    • Oct 2016
    • 103

    Want to convert a HA 5.56 to 6.5 Grendel

  • LRRPF52
    Super Moderator
    • Sep 2014
    • 8569

    #2
    Depending on your accuracy requirements, it is a fairly simple process to do, like building any other AR.

    Most of your $200-$350 barrels will hover around 1 MOA. Some will shoot better, and some over that with brass-cased, US-made ammo.

    Your $400+ barrels will shoot MOA better, as long as they are installed in a tight upper with a good trigger, balanced scope mount torque specs, quality scope, quality ammo, good build approach.

    If you take the build process to a more advanced level with receiver face squaring, bedding/press-fitting, sealing the gas block and tube, tuning the bolt, ejector, extractor, lug lapping, it can get more involved like any other accuracy build.

    The accuracy build approach will have much more discriminating parts selection, starting with the barrel and upper receiver, as well as the fit of the gas block to the journal, gas tube quality, additional tools, adhesives, and familiarity with little details of the AR15 that are commonly-overlooked.

    If you just want to smash party together, it's like any other AR15 with a simple bolt/barrel/magazine switch. Your muzzle devices use larger thread patterns like on 7.62 rifles.

    Hiccups that are common and unique to the larger cartridge:

    * Ejector face too sharp catches the side of right hand magazine feed presentations. Needs to be recessed and/or radiused to prevent binding and FTFeed malfs.



    * Gas block needs to be bedded or press-fit for reliability (any AR15/AR10)

    * Gas tube should press-fit into the block. If not, it will allow leaking and insufficient gas to the action. I bed mine. LaRue has a nice gas block with a ferrule pressed into the block around the tube to seal off the gas. KAC has their own proprietary system that threads onto the barrel, with a hydraulic line type seal on the gas tube. There's another company that recently copied this method that introduced it at SHOT as "innovation". ArmaLite used a brake line type has tube seal on the SASS as well many years ago.

    I also personally blend and polish my feed ramps, but this isn't necessary unless you have a poorly-matched upper and barrel extension and want to shoot hollow points. Applies to .223 and .308 as well.

    A big thing you have to look out for is manufacturers making 18" MLGS barrels with .094" gas ports, which are .018" too large. For some reason, there are a lot of these out there, and they should never have been cut that large. These guns will be gassed so hard, you'll have early unlocking, stove pipes, FTFeeds, insane carrier bounce, just bad news all around, unless the gas blocks are so loose initially that they bleed off excess gas until the carbon up and then start slamming the system to death.

    Recoil will be noticeably heavier with 6.5 Grendel unless you shoot with a brake, tuned gas system, tuned recoil system, which can feel like shooting .22 LR. It isn't so bad that they are intolerable, and smaller kids can shoot them comfortably. Since we're shooting heavier bullets, a lightweight AR15 will want to jump around on you more than a .223 will, so they have to be driven with very disciplined approach to the fundamentals. Most lighter weight Grendels and AR10s are very unforgiving of poor technique, whereas a .223 AR will let you get away with a lot, especially with a good trigger.
    NRA Basic, Pistol, Rifle, Shotgun, RSO

    CCW, CQM, DM, Long Range Rifle Instructor

    6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

    www.AR15buildbox.com

    Comment

    • StoneHendge
      Chieftain
      • May 2016
      • 2009

      #3
      You actually only need the bolt and can use your existing carrier. And if you want to use your existing gas block, make sure the new barrel will have the proper diameter at the gas block. And the same gas system length, although a good gas tube is only around $15.
      Let's go Brandon!

      Comment

      • va_connoisseur
        Warrior
        • Oct 2016
        • 103

        #4
        Originally posted by LRRPF52 View Post
        Depending on your accuracy requirements, it is a fairly simple process to do, like building any other AR.

        Most of your $200-$350 barrels will hover around 1 MOA. Some will shoot better, and some over that with brass-cased, US-made ammo.

        Your $400+ barrels will shoot MOA better, as long as they are installed in a tight upper with a good trigger, balanced scope mount torque specs, quality scope, quality ammo, good build approach.

        If you take the build process to a more advanced level with receiver face squaring, bedding/press-fitting, sealing the gas block and tube, tuning the bolt, ejector, extractor, lug lapping, it can get more involved like any other accuracy build.

        The accuracy build approach will have much more discriminating parts selection, starting with the barrel and upper receiver, as well as the fit of the gas block to the journal, gas tube quality, additional tools, adhesives, and familiarity with little details of the AR15 that are commonly-overlooked.

        If you just want to smash party together, it's like any other AR15 with a simple bolt/barrel/magazine switch. Your muzzle devices use larger thread patterns like on 7.62 rifles.

        Hiccups that are common and unique to the larger cartridge:

        * Ejector face too sharp catches the side of right hand magazine feed presentations. Needs to be recessed and/or radiused to prevent binding and FTFeed malfs.



        * Gas block needs to be bedded or press-fit for reliability (any AR15/AR10)

        * Gas tube should press-fit into the block. If not, it will allow leaking and insufficient gas to the action. I bed mine. LaRue has a nice gas block with a ferrule pressed into the block around the tube to seal off the gas. KAC has their own proprietary system that threads onto the barrel, with a hydraulic line type seal on the gas tube. There's another company that recently copied this method that introduced it at SHOT as "innovation". ArmaLite used a brake line type has tube seal on the SASS as well many years ago.

        I also personally blend and polish my feed ramps, but this isn't necessary unless you have a poorly-matched upper and barrel extension and want to shoot hollow points. Applies to .223 and .308 as well.

        A big thing you have to look out for is manufacturers making 18" MLGS barrels with .094" gas ports, which are .018" too large. For some reason, there are a lot of these out there, and they should never have been cut that large. These guns will be gassed so hard, you'll have early unlocking, stove pipes, FTFeeds, insane carrier bounce, just bad news all around, unless the gas blocks are so loose initially that they bleed off excess gas until the carbon up and then start slamming the system to death.

        Recoil will be noticeably heavier with 6.5 Grendel unless you shoot with a brake, tuned gas system, tuned recoil system, which can feel like shooting .22 LR. It isn't so bad that they are intolerable, and smaller kids can shoot them comfortably. Since we're shooting heavier bullets, a lightweight AR15 will want to jump around on you more than a .223 will, so they have to be driven with very disciplined approach to the fundamentals. Most lighter weight Grendels and AR10s are very unforgiving of poor technique, whereas a .223 AR will let you get away with a lot, especially with a good trigger.

        Comment

        • King31
          Bloodstained
          • Oct 2016
          • 70

          #5
          I would recommend the group buy 18" Faxon and Monster bolt. After that just grab some Cproducts mags and you are ready to assemble it and shoot!
          Trevor | NRA Life Member

          Comment

          • Lastrites
            Warrior
            • Apr 2017
            • 678

            #6
            And ya'll should take a close look at that photo above as it is worth a 1000 words, especially the ejector.

            Oh, "ya'll" included for the Grammar lesson provided elsewhere, lol and I enjoyed that thread.

            Comment

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