PDW 12" Build

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  • LRRPF52
    Super Moderator
    • Sep 2014
    • 8569

    PDW 12" Build

    Here's where I'm at with the 12" Grendel parts, with a ThunderBeast Ultra 5 in jail since October.

    I have the Maxim Defense PDW Brace in FDE ordered with the SHOT Show special deal.

    Not sure which lower I'm going to use on the 12".

    Now that LaRue sells the upper and handguard kit for the Stealth 2.0, I'm tempted to get that instead of what I have here. I really like the slim profile of the Stealth 2.0 and the lock-up of the handguard to the upper, since it doesn't tough the barrel at all.

    Faxon Group Buy 12" barrel

    I have at least 3 different bolts to choose from, including AA hard use, forum group buy, and Maxim/PF nitrided.

    That's a Bootleg adjustable bolt carrier with 4 positions.

    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
  • ClutchAutomatic
    Warrior
    • Jan 2018
    • 121

    #2
    Very nice man!

    Comment

    • danm
      Warrior
      • Aug 2014
      • 498

      #3
      LIKE!!! Is this the first 12" G that you've owned?

      Comment

      • Keef
        Warrior
        • Jun 2017
        • 296

        #4
        That's going to be awesome.

        Comment

        • Kswhitetails
          Chieftain
          • Oct 2016
          • 1914

          #5
          I'm jealous of your PDW brace. Sorry to have missed that one. Are these parts all self-cerakoted?

          I too, am looking at the Larue 2.0 set, though that would be way outside the envelope of my builds intended envelope. I don't consider Larue gear "throw around use" stuff - it hurts my sensibilities. He would probably think that's dumb, and get more entertainment out of being rough with it... I wonder what would happen to the warranty if I sent in a broken upper because "the seat rolled over it when I was adjusting my seating position for better visablility." LOL

          What about an FDE A-Peg? I am liking mine more and more, I didn't think I did at first. The more I handle it the more it grows on me, to my actual surprise.

          I enjoy watching folks with a whole bunch more experience than myself posting about their building progress. I learn a lot from you, thanks for what you share.
          Nothing kills the incentive of men faster than a healthy sense of entitlement. Nothing kills entitlement faster than a healthy sense of achievement.

          Comment

          • Lastrites
            Warrior
            • Apr 2017
            • 678

            #6
            Haven't really read too many reviews on the PDW with their specialized shortened bcg, how do these things really work/run, do they run well? Back in the day I recall all sorts of issues with short tubes from a company called GRS iirc and most everyone steered a clear path around them as we were building AR pistols. If I recall they used a recoil spring about the size of one found in a 1911.

            Comment

            • LRRPF52
              Super Moderator
              • Sep 2014
              • 8569

              #7
              Neither the SB Tactical nor the Maxim Defense need special BCGs.

              The SB Tactical uses standard length RET and carbine buffers. In the pics, there is a JP SCS in mine.

              The Maxim Defense uses a special short buffer and spring included in the package.

              The Maxim Defense allows shorter weapon overall length (more compact), and longer length of pull at full extension compared to the SB Tactical, plus it has QD sling swivel sockets on the sides of the central housing of the unit.
              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

              • 82HALO
                Warrior
                • Nov 2015
                • 181

                #8
                I was lucky enough to get in on the maxim buy! This thing is awesome! Was looking to pick one up with the JP spring, but, couldn't pass this one up! Will also be using this with my 12" GB barrel!

                Comment

                • explorecaves
                  Warrior
                  • Sep 2014
                  • 284

                  #9
                  you, ummm... have a couple extra parts there.

                  Comment

                  • Keef
                    Warrior
                    • Jun 2017
                    • 296

                    #10
                    Have you assembled it yet? Pic?

                    Comment

                    • LRRPF52
                      Super Moderator
                      • Sep 2014
                      • 8569

                      #11
                      I went to assemble using my approach.

                      Everything seemed fine with troubleshooting before final, then once I had the gas tube in, two different bolts would not lock-up in the extension.

                      They lock up fine before the tube is installed, and the alignment with the tube is about perfect upside-down with a stripped carrier.

                      I measured my offset for gas block location from the shoulder, and determined I could go up against the shoulder and still have coverage, but I suspect that the flange on the gas tube is binding in the carrier key, causing the bolt to bind in the extension.

                      The amount of torque I have to apply to get handguard alignment is also such that it's messing with clocking of the extension, which prevents one bolt from entering the extension on closure/lock-up.

                      I've seen this before on rare occasion, and will bed the barrel again overnight, then use shims with the barrel nut to reduce torque.

                      I got called for some honey-do so just broke all the parts down and put them back in the Build Box for later.

                      I've been working crazy hours lately, so not much time to mess with it just yet, although I'm very anxious to get her running.

                      I'm looking at running the 130gr Nosler RDFs out of this for long range as a proof of concept for a 1000yd PDW system, that also covers down on CQB distances with superior barrier defeat to pretty much anything else out there.
                      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

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