Barnes 100gr TTST - 8208 - Magnetospeed Sporter

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  • dmsims21
    Warrior
    • Nov 2012
    • 430

    Barnes 100gr TTST - 8208 - Magnetospeed Sporter

    Just worked up a great load for the Barnes 100gr TTSX over 8208.
    I need to give credit to PA_Allen, as I saw 30.0gr of 8208 from him first.
    It worked out well for me- 5 shots in 0.85" with my Magnetospeed Sporter connected.

    Load Data
    Lilja 18" 319

    100gr TTSX
    30.0gr 8208
    OAL 2.26"
    Lapua Brass (twice fired and trimmed)
    CCI 450
    5 shots - 0.85" @ 100yds

    Avg Vel - 2700fps
    StdDev 8fps
    (once again, 8208 puts up very consistent velocities)

    Magnetospeed Sporter thoughts.
    Once I got used to the chrono, I really liked it. It took a little bit to get used to the controls. I found it easiest to download the shot strings to my phone (requires an aditional adapter).
    The sporter definitely changed the POI by about 2" at 100 yds.
    I shot the 0.85" group with the Sporter attached. I didn't shoot an additional group without it, but I don't think it affected the group size much. I can't shoot much better than that group.

    20150803_194455.jpg
    www.FriendsvillePrecision.com - AR15 Dry Fire Device
  • JPShooter
    Bloodstained
    • Jul 2015
    • 39

    #2
    I'm currently waiting for delivery of my first Grendel upper from AA and saw your post, as I also have a Magneto Speed. I've some concerns on using it for load development and thought I might share them. If you feel that I'm hijacking your thread I will gladly move this to another. Please don't hesitate to state so.

    First off, I really like the chrono a great deal. It's so easy to slip it on the barrel and step outside my shop (I live rural) and send a round into the dirt and see what it's doing speed wise. I don't have the room for a range, but I can safely and legally discharge a firearm on my property. So as a tool to quickly determine velocity of a given load it's very handy not having to go to the range and shoot through a traditional chronograph.

    My thought regarding load development is in line with your statement regarding the POI shift (well noted by others as well) that you mentioned. If the POI is shifted, then my question is, then are not the harmonics of the barrel changed? If we are developing loads and trying to find the best velocity based on the harmonics of the barrel (the node), then are we not fooling ourselves as to what we are seeing with a device hanging on the end of the barrel?

    It seems to me that the downfall of the Magneto Speed is the potential to have a load worked up (while the Magneto Speed is mounted) and then find that the grouping changes (not just the POI) when the device is removed. I can't answer these concerns myself as I have not used it in this manner. I tend to develop a load and then see how fast it is.

    Thoughts?

    Comment

    • JASmith
      Chieftain
      • Sep 2014
      • 1620

      #3
      I have put. Over 700 rounds over my Magnetospeed and have become comfortable using it.

      Yes, the harmonics are affected. I have not, however, been able to determine which way the group size changes. I do know the direction of the POI shift depends on how much cant one allows when mounting the Magnetospeed.

      My thiughts for folks working up accuracy loads:

      1) Run a 5 to 10 shot ladder over the range of charges one is interested in.

      2) Then plot the resulting velocities and draw an average line. The average line will get you pretty close to the velocity your ultimate favorite load for that powder amd bullet will turn in.

      3) Work up the accuracy load keeping in mind the velocity and pressure indications inferred fromthe first ladder.

      4) Run the resulting favorite load over the magneto again to verify velocity.
      shootersnotes.com

      "To those who have fought and almost died for it, freedom has a flavor the protected will never know."
      -- Author Unknown

      "If at first you do succeed, try not to look astonished!" -- Milton Berle

      Comment

      • dmsims21
        Warrior
        • Nov 2012
        • 430

        #4
        I guess it possible that the Magnetospeed would change the harmonics enough to make a certain load shoot better with it attched. It is also possible that it could really open up a group that would otherwise be really good.

        I think from here on out, I will load up 2 rounds at each charge weight and shoot them with the Magnetospeed. Then I can I can get a velocity trend line and discover any loads with inconsistent velocity.
        Next, I will shoot groups without the Magnetospeed. Then confirm the velocity of the best group with another batch.

        The only problem is that a certain load may have very consistent velocity, but not group well at first. A small change in seating depth may tighten it up. If you shoot all of your groups without the Magnetospeed, you would miss it.

        I will try to shoot the same load without the Magnetospeed attched to see if the group size changes.
        www.FriendsvillePrecision.com - AR15 Dry Fire Device

        Comment

        • wraith1516
          Warrior
          • Dec 2014
          • 316

          #5
          Out of my 20"lbc bhw barrel im getting 2713f/s (using an older model crony) with 30 gr 8208xbr ttsx100 gr bullets and#41 primers

          Comment

          • JASmith
            Chieftain
            • Sep 2014
            • 1620

            #6
            Originally posted by dmsims21 View Post
            I guess it possible that the Magnetospeed would change the harmonics enough to make a certain load shoot better with it attched. It is also possible that it could really open up a group that would otherwise be really good.
            ...
            ...I will try to shoot the same load without the Magnetospeed attched to see if the group size changes.
            Remember that statistics are not our friends in these endeavors. There will be a chance that one or both groups is far enough from their respective population averages that one sees the opposite of the true relationship.
            shootersnotes.com

            "To those who have fought and almost died for it, freedom has a flavor the protected will never know."
            -- Author Unknown

            "If at first you do succeed, try not to look astonished!" -- Milton Berle

            Comment

            • dmsims21
              Warrior
              • Nov 2012
              • 430

              #7
              You are right JASmith. The limited testing we do while working up loads is subject to many more variables than we understand. Many times our results are reproducible, but only in a certain rifle, under certain circumstances.
              We may skip over a load with 0.5MOA capability, because we can only shoot 0.75 at our best and 1.0 on average.

              To me, reloading is about having fun and maybe saving some money.
              www.FriendsvillePrecision.com - AR15 Dry Fire Device

              Comment

              • JASmith
                Chieftain
                • Sep 2014
                • 1620

                #8
                Amen brother!

                ...but then it is too easy to get way down in the weeds of detail!
                shootersnotes.com

                "To those who have fought and almost died for it, freedom has a flavor the protected will never know."
                -- Author Unknown

                "If at first you do succeed, try not to look astonished!" -- Milton Berle

                Comment

                • Coty
                  Unwashed
                  • Sep 2015
                  • 21

                  #9
                  This is my standard hunting load, also used PA_Allen's load data. My spreadsheet shows 2732 fps with a suppressor and 18" barrel. This is my 3rd season as my primary hunting rifle. Previously hunted with a .270 and a 450 Bushmaster. I've had great results hunting with the 100 gr TTSX.

                  Comment

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