IMR 8208-XBR and the Grendel

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  • IMR 8208-XBR and the Grendel

    ... except....ADI AR 2210* and adjust case capacity from a measured 36.3 to 39gr H20, I get a velocity match, but at 53.7ksi)
    **Using H322 and/or ADI 2219 gets the same result, so the ADI MSDS sheet appears to be correct:


    The XBR velocity result was a total surprise as it easily matches the ball powders, but is ~100-150fps faster than any of the other stick powders. Primers are no good for pressure signs and I'm obviously under the 70ksi brass-flow/ejector smear regime.

    `Anyone else getting similar (or different) results, and does anyone have a handle on the pressures ?




    postscript: I've found that adjusting QuickLoad case volumes show consistent relationships between stick powders (use 36.gr H2O) and ball powders (use 40gr H2O). So XBR is acting like a ball powder as far as QL is concerned.
  • PA_Allen
    Warrior
    • Mar 2011
    • 333

    #2
    Your results seem reasonable and close to what others have reported here. I get almost exactly the same velocity as you do out of my 20" barrel with 28 gr of 8208 behind the 120 gr NBT. Full results posted here:

    I finally was able to pick up a pound of XBR 8208 to try. I only had time to try a few loads with the 100 gr and 120 Nosler Ballistic Tip Bullets. All of the loads were fired through my 20" Lothar Walther Barrel with the CSS chamber. Chronograph screens 12 ft. from muzzle, all velocities reported from chrono. (not


    Notice that hodgdon data reports almost 2500 fps with 8208 and the 123gr Sierra.

    I do appreciate your caution. I too was suprised at the velocities that I was able to achieve with this extruded powder in the Grendel case. I want to do some more testing, but I am cautiously optimistic that that 28 gr with 120 gr class bullets is a safe and great performing load.


    Thanks for sharing.

    Best,
    PA

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    • #3
      That's great info, thanks for sharing

      Comment


      • #4
        I tried 28 with a 123 amax. It worked great and shot very accurately. I had just cleaned the barrel. Shots 1-5 were 1.25". Shots 6-10 were moa. Shots 11-15 were excellent. This load will get more use soon.

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        • #5
          I was using 28.4g 8208XBR Lapua case 450's and 123 Scenars. They shot 1/2" groups out of my 19.5" Shilen. Problem was when it warmed up the load was too HOT. I backed down to 28.1g and can now shoot this load winter or summer, also groups are 1/2"

          in my experience 8208 XBR is not as temperature stable as IMR would like us to believe.

          Edit: I was getting 2538 fps with the 28.4 load. Have not re chronoed at 28.1 yet.
          Last edited by Guest; 02-04-2012, 07:05 PM.

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          • #6
            What primers are yall using? Im using Lapua cases mostly

            Comment

            • bwaites
              Moderator
              • Mar 2011
              • 4445

              #7
              Either CCI 450's or Wolf Small Rifle Magnum.

              Wolf Small Rifle Magnums have been more consistent for lots of folks.

              Comment


              • #8
                IMR8208XBR uses the same formulation as Varget and is made in Australia at the same plant but is a finer extrusion. All powders are temperature sensitive, but in my experience 8208 is the least sensitive of all powders available when it first came out. The story of it's development was quite interesting as written up in Hodgdon's annual publication a couple of years ago, unfortunately I lent my copy out and it has never returned. However, as memory serves me the story goes something like this;
                A mythical powder prized and coveted by bench rest competitors called Thunderbird had become nearly impossible to obtain and costly when located. A serious bench rest shooter from Texas inquired of Hodgdon what the cost would be to reformulate Thunderbird. They responded with a quote of $170,000 or a similar figure expecting the inquiry to go away, instead a check arrived with instructions to proceed. So Hodgdon launched a project to duplicate Thunderbird. One of the attributes of thunderbird was that it was stable over varying conditions and temperatures, so much so that bench rest shooters, who typically load on location at matches to the conditions of the day could often get by with a standard load.
                Before Hodgdon had gone very far in the development, one of the engineers reported that he had tested a powder from Australia with nearly identical properties of Thunderbird. He further advised this powder should be evaluated against the specifications before further work was done on a new formulation. They tested and confirmed the development work had already been done the new Thunderbird was already available. So, Hodgdon contacted the bench rest competitor and asked if he would like to have his check back and a new powder to test to which he agreed. He shot this new powder designated as IMR8208XBR for the entire season, a single loading for all conditions and won the national championship with that load that year, I believe it was 2009. I don't remember the class but it wasn't unlimited, perhaps heavy varmint but I can't remember for sure.
                I then had a conversation with Troy Lawton, who is the individual who chooses components for the Army Marksmanship Unit at Camp Benning. Troy was testing different powders and lots in combinations of other components for their service rifle teams .223 short line and long line loads. He told me one of the powders he had very impressive results with was IMR8208XBR and that I should consider it but would not say what they had chosen for that years loads. So, I began developing loads for both my Grendel and my .223 Service Rifles and found the powder to meter well, have ideal density, burn clean, and to be very accurate so I adopted it in late 2009.
                The first full season I shot it was 2010 and just completed the 2011 season so I've now shot this powder in around 50 to 60 matches all over the nation, including Camp Perry Ohio, Camp Butner North Carolina, River Bend Georgia, Camp Benning Georgia, Fort Gordon Georgia, Phoenix Arizona, Palm Bay Florida and many others from as low as 20 degrees to as high as 107 degrees. My data books show the most consistent zero's I've ever enjoyed and many personal best scores and many matches won with this powder so I kind of like it.
                Bob

                Comment


                • #9
                  Interesting story. Thanks for sharing that. The history behind things really peaks my interest because you can't make the stuff up usually.

                  Comment


                  • #10
                    I have a copy of that annual and that's a pretty good synopsis.

                    Comment


                    • #11
                      Anyone having quality problems with the Wolf primers? Out of 40 I had 10 no fires. More than a little disappointed

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                      • bwaites
                        Moderator
                        • Mar 2011
                        • 4445

                        #12
                        No, it's not the primers.

                        What trigger and which Wolf Primers?

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                        • Drifter
                          Chieftain
                          • Mar 2011
                          • 1662

                          #13
                          I agree with bwaites; the primer issue is probably with the trigger, and / or hammer spring strength.
                          Drifter

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                          • bwaites
                            Moderator
                            • Mar 2011
                            • 4445

                            #14
                            Here's some interesting info, I especially noted the results with the 6 PPC, the direct
                            parent of the Grendel.

                            Last edited by bwaites; 02-21-2012, 12:12 AM.

                            Comment


                            • #15
                              They are small rifle magnums. I believe it a jp trigger. I thought it was a soft trigger but even tried them right away in a friends Grendel with a Timney trigger as he said the same thing, but they still wouldnt fire.

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