New 24 inch barrel Grendel built

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  • Glock357
    Bloodstained
    • Jun 2016
    • 50

    New 24 inch barrel Grendel built

    Hi guys this pretty much my first post. I got my shipment of a new barrel a couple of days ago and was able to put it together in about 6 hours over three nights.
    Here is my list of parts:
    Upper:
    • Brownells medium profile 24 inch SS Grendel II barrel: 1:8, 5R, rifle gas port made by Satern
    • YHM gas tube, low pro gas block, thread protector
    • Hogue rifle length free float
    • Leapers bipod (custom installed)
    • PSA forged upper receiver with PSA parts kit
    • Old bolt carrier I had, don't remember details and bot that came with barrel

    Not mounted yet: Vortex viper HS 4-16 x 44. Vortex scope rings coming tomorrow.
    Lower:
    • Engage armament billet lower receiver (local gun store custom)
    • velocity single stage drop in trigger
    • Hogue grip
    • Magpul stock
    • JP enterprises silent captured spring buffer


    Installation:
    1. Squared upper receiver with Brownells tool
    2. Bedded barrel with blue locktite
    3. Torqued barrel nut with strap wrench. After applying loctite anti seize
    4. Drilled and tapped free float tube to mount sling stud. Also added an extra #10x32 SS Philips screw through the Picatinni rail of the UTG bipod mount for additional support
    5. Torqued free float with strap wrench with anti seize
    6. Lower install standard. I didn't include the buffer retainer because it's a pain to get the JP buffer out with it.


    I am considering grinding and polishing the upper in order to mate it with the M4 feeding ramp lips. The feed ramps need polishing anyway (they came rough finished and not polished). I usually hand load to mag length and worried that if rounds hit the upper receiver it will push the bullets in. Do you guys typically do this?

    Can't wait to shoot it!

    Anyway, I need to go cleanup my mess now
    image.jpegimage.jpegimage.jpegimage.jpeg
  • Glock357
    Bloodstained
    • Jun 2016
    • 50

    #2
    Mounting the Vortex Viper HS scope

    I received the 2 inch offset vortex mount so I went ahead and mounted the scope. After finding my preferred position I tightened the mount to the Picatinni rail of the upper and finger tightened the rings so that I would align the reticle with upper rails flattop. I then used my iPhone as a bubble surface level first on the Picatinni rail then on the flat surface of the elevation cap. I then rotated the scope such that the angle of the Picatinni and the scope matched. The iPhone level has an accuracy of 0.1 degrees, which is about the same as any digital level and much better than any bubble level. I then tested how well I mounted the bipod. The Picatinni rail I installed for the bipod is parallel with the Picatinni of the receiver within the level's accuracy. When I installed the bipod it was off by 1 degree when the bipod is at its shortest length. This means that the bipod is uneven. Not too much though. At the bench or at the field I'll be able to correct for that by adjusting the height of the bipod feet.
    image.jpegimage.jpegimage.jpeg

    Edit:

    Well this didn't work. For some reason the vortex top cap is not parallel to the reticle so aligning the scope with it didn't quite work. I ended up aligning the reticle to a plump line at 60 yards, after I ensured the top receiver was level. I also added a 20 MOA Weaver Picatinni rail. This raised the scope giving me a more comfortable shooting position when I wear my earl muffles. I verified reticle alignment at the range by shooting at a plumb vertical line at 100 yards in the middle, then dialing elevation all the way up and then all the way down. The groups landed nicely on the vertical line.
    Last edited by Glock357; 07-17-2016, 07:50 PM. Reason: Didn't work

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    • Glock357
      Bloodstained
      • Jun 2016
      • 50

      #3
      Review of the vortex 2 inch offset mount

      The mount looks really nice. There is great attention to detail when machining and all the small pieces mate together as if they were cut from the same block. The mount's curves are streamlined and I like the flash receded torx screws. Perhaps I went too far with the 2 inch offset because when I push the scope down by the objective lens the mount flexes noticeably. When I tried to flext my Burris PEPR mount I have on my Nikon scope I can't see any flex. I don't know how flex will affect anything, but it's there.

      Comment

      • Glock357
        Bloodstained
        • Jun 2016
        • 50

        #4
        I forgot to mention. The weight of the finished rifle is 12 lb even! Not bad for a 24 inch semi automatic rifle. If I want to take it hunting I also have another lower with a light Magpul retractable carbine stock which should shave off a pound or two.

        Comment

        • Glock357
          Bloodstained
          • Jun 2016
          • 50

          #5
          Range report

          I went to the range yesterday. I shot some factory Hornady 123 gr Amax as well as some hand loads I was working up. (I will post details about my hand loads in the reloading sections)

          For barrel break-in I would shoot 10 rounds and clean the barrel and repeat. I did notice a significant increase in velocity after I cleaned the barrel after the first 10 rounds but then things were constant. (From avg velocity 2563 to 2648 fps)

          Accuracy: factory ammo 100 yards: 1.1 inches, average 20rd velocity 2645fps, std 21, 88F
          200 yards: 1.25 inches
          Hand loads 100 yards: 0.81 inches, Amax, benchmark 27gr, 2500fps, std 14
          I was shooting off a bench rest using only a bipod.

          I was surprised how fast the factory loads were! Faster than the 120 gr SST in my 6.8 SPC, 20 inch barrel. However they were really hot and I noticed cratering in the primers!
          image.jpeg
          100 yards factory
          image.jpeg
          200 yards factory
          image.jpeg
          100 yards Hand load
          image.jpeg
          100 yards factory
          image.jpeg
          Factory load is really hot!
          Last edited by Glock357; 07-17-2016, 08:37 PM.

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