Loads and shooting for 16" Faxon Gunner

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  • grayfox
    Chieftain
    • Jan 2017
    • 4295

    Loads and shooting for 16" Faxon Gunner

    So, I've been working on my 16" gunner, new Grrr build, doing load checks; well, finally got to adjusting my AGB and re-checking loads.
    This is just a JoeBob AGB and doesn't have detents but I picked up a couple of them and so far, things are ok. Rather than starting closed and clicking open 1 click at a time, I measured the travel from full open (with the bottom of the adj screw right at the entry into the port/gas flow) to fully closed: 6.5 turns of the allen wrench. I figured I would narrow down to my opening by going "halfsie's": shutting down basically (more or less) 1/2 the full travel distance, do the check, and open or close 1/4 depending on results, etc, in ever smaller 1/2 of the remainder.

    I picked factory 123sst ammo as my test rounds, then planned to check the others once I determined the throttle for the 123sst. Fully open of course it locked back sat. Went to 3 turns closed (roughly half-way) and the round still locked the bolt back properly. Went to 4 T closed, 123sst locked back sat. 5 T closed, 123sst locked back sat. OK, now I was at only 1.5 T open on the GB, what to do? I "chickened out" and left it there at 5 closed.... tried a different round, Federal factory 120 MSR. At 5.0 closed the MSR locked back on the mag and not on the bolt catch. So I figured I had reached my max closing amount if not a bit too much. Adjusted back to 4.5 T closed, and the MSR cycled Sat. So now with 2 loads cycling Sat, I tried my 100 Amax and 90 TNT loads, and they cycled and locked back Sat as well. Great! So I'm leaving it at 4.5 T closed (from the full open). Tightened the setscrew down and I'm rockin' and rollin'.

    Now for some re-checks of MV from my loads, back to the range and tried them all today, everything cycling sat and my trusty magnetospeed gave me the results:

    For 90 TNT (31.2 H335), 100 Amax (29.7 XBR), 123sst (30.8 CFE), 123Factory, 120MSR and 123 Black(factory).

    Bullet, Powder, (gr), 1, 2, 3, 4, -- Avg, SD, ES
    90 TNT, H335, 31.2, 2675, 2689, 2704, 2696,-- 2691, 12.3, 29
    100 Amx, XBR, 29.7, 2653, 2660, 2660, 2638,-- 2653, 10.4, 22
    123 sst, CFE223, 30.8, 2427, 2421, 2408, 2413,-- 2417, 8.4, 19
    123 sst, Fact , -, 2427, 2439, 2452, 2448, --2442, 11.1, 25
    123 HdBk Fact , -, 2375, 2359, 2378, 2361, 2368,-- 9.6, 19
    120 MSR Fact , -, 2416, 2426, 2422, 2409, 2418,-- 7.4, 17

    Comparing this to my MV checks before adjusting the GB didn't show much change, as Stonehenge had commented on another thread... but I do perhaps see a little tightening up on the 120 MSR as the SD went from 14 down to 7. And there could be some mv gain on the 123sst factory where it had been 2405 but now shoots 2442 Avg (same box of ammo).

    It could be that there's no statistical difference as the delta's are relatively small and not consistent across the several loads... perception-wise however I do think it is shooting "more smoothly" than before. I'm pretty happy that factory as well as my fave loads are still doing well however. And looking forward to tweaking the AGB on my 18" faxon Group barrel next.
    "Down the floor, out the door, Go Brandon Go!!!!!"
  • LRRPF52
    Super Moderator
    • Sep 2014
    • 8569

    #2
    Good deal finding your window early like that with 4 different loads.

    No measurable diifference in mv has been observed in fleet testing with shut-off and open gas.
    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

    • grayfox
      Chieftain
      • Jan 2017
      • 4295

      #3
      My 18" group buy barrel, "18F" (F for Faxon, gotta name them somehow so I can keep them straight in my mind), is next.....
      Info from you guys and commentaries on here, plus some benchwork, definitely is yielding results. As a small kudos the Faxon barrels are proving easier to load for than a couple of other brand (now retired) barrel I had! So a big Thanks to BFT of all the mfrs to work with he picked a good one.
      "Down the floor, out the door, Go Brandon Go!!!!!"

      Comment

      • StoneHendge
        Chieftain
        • May 2016
        • 2009

        #4
        You need to get more creative with your names

        F2F84ADE-8727-4BBA-8052-28E8F4958B19.png
        Let's go Brandon!

        Comment

        • grayfox
          Chieftain
          • Jan 2017
          • 4295

          #5
          That's a BAAAAAAD list bubba!
          I'm afraid my creative names might be too politically incorrect...
          "Down the floor, out the door, Go Brandon Go!!!!!"

          Comment

          • StoneHendge
            Chieftain
            • May 2016
            • 2009

            #6
            Yeah, best to keep it clean. Wouldn’t want a politically incorrect list to make it into a jury’s hands in a self defense trial.
            Let's go Brandon!

            Comment

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