Unconfigured Ad Widget

Collapse

300 BLK - load data with Unique

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • ER308
    Member
    • Jan 2013
    • 135

    300 BLK - load data with Unique

    Sharing some load data. None of the loads below showed any signs of high pressure.

    300 AAC Blackout/Whisper
    AAC Model 7 - 16"
    (velocities are average of 5 shots through two chronographs)

    bullet powder wt grns velocity fps comments
    Missouri 245 cast Unique 5.6 997
    Missouri 245 cast Unique 5.8 1014
    Missouri 245 cast Unique 6.0 1042
    Missouri 245 cast Unique 6.4 1072
    Missouri 245 cast Unique 6.8 1116
    Missouri 245 cast Unique 7.2 1153 very large groups
    Missouri 245 cast Unique 7.6 1187
    Xtreme 150 plated Unique 5.4 1140
    Xtreme 150 plated Unique 5.6 1144
    Xtreme 150 plated Unique 5.8 1168
  • #2
    ironhorse1
    Senior Member
    • Nov 2012
    • 1004

    Be very afraid!

    I have no experience with the .300 but the posted loads leave me concerned for your safety.

    Using a 245 grain cast bullet with 7.6 grains of Unique has got to produce more pressure than a .357 using 7.7 grains of Unique with a 158 grain jacketed bullet.

    Just because you see no pressure signs does not mean you are not over pressure in your loads.

    My only holy crap moment with Unique was when I tried 7.5 grains in and .30 carbine pistol with 110 grain bullet.

    Recoil and blast was loud and the primers were flat and the cases needed to be forced out of the cylinder.

    Unique at top end loads will generate a lot of pressure quickly and that is why its best use is medium loads.

    I'm looking forward to additional input on this thread.

    irh

    I noticed that the last three 245 grain loads gained very little velocity despite the increase in the powder charge.

    This is what happens when a powder is maxed out and all you get is increased pressure without an increase in velocity.
    Last edited by ironhorse1; 12-05-2015, 12:39 PM. Reason: more info

    Comment

    • #3
      ER308
      Member
      • Jan 2013
      • 135

      Thanks for the concern. I have seen others go as high as 8.2 with no problems. Really... the primers showed no difference from the low to the high loading. Perhaps this is of the much higher operating pressure of the rifle round. The intent was to establish a stable subsonic load. The 5.6 gr load was quite accurate and is my recommendation. I believe the reason for the gross inaccuracy of the 7.2 gr load is that it right at the transition from sub to super sonic and is probably experiencing a lot of turbulence a expected. I expected that in theory, but cool to see it play out in this test.

      Comment

      • #4
        ER308
        Member
        • Jan 2013
        • 135

        Also, if you plot velocity vs powder weight, you will find a very linear relationship, so it is not 'topping out', as you suggested. Thanks for your concern.

        Comment

        • #5
          ironhorse1
          Senior Member
          • Nov 2012
          • 1004

          Originally posted by ER308
          Also, if you plot velocity vs powder weight, you will find a very linear relationship, so it is not 'topping out', as you suggested. Thanks for your concern.
          On a chart it would appear to be true. If you divide velocity by weight charge

          you have topped out in the 6.8 - 7.2 loads and are getting less velocity per grain at the 7.6 grain load.

          Knowing the properties of Unique, even small increases in charge weight, will increase pressure without much added velocity.

          You usually won't know you are over pressure until something bad happens.

          You might want to try another powder such as 4227, IMR 4198 or Reloader 10X.

          As far as turbulence affecting group size I doubt it. Perhaps the top load listed is causing issues with the bullet base, if not gas checked, with Unique powder.

          Do the math and you will see the slow reduction of velocity per grain as your load increases.

          If it can be done safely I would like to see more data with different powders with the cast bullet.

          I hope others have some additional experiences to share.

          irh

          Comment

          • #6
            ER308
            Member
            • Jan 2013
            • 135

            The math you are proposing in that fps/charge weight decreases as you go up is true for just about every safe load sequence. Just apply what you have suggested to any loading manual and you will see that. That's not an indicator of an unsafe load. I know your intent here is good, and I don't propose anyone load anything that they are uncomfortable with, but the numbers and observations I generated on this are not suggesting anything unsafe. With regards to the inaccuracy, the turbulence I think is real, as the groups tightened back up with the next higher loading at 7.6 grains. The intent of this test was to specifically test a pistol powder, to achieve a reasonable subsonic velocity while minimizing gas generation (and noise). Compared to a load achieving similar velocity with a slower powder (H-110), the Unique loads were quieter.

            Comment

            • #7
              Spaceghost
              Calguns Addict
              • May 2006
              • 5772

              Does the the action cycle with these loads?

              Comment

              • #8
                ar15barrels
                I need a LIFE!!
                • Jan 2006
                • 57122

                Originally posted by ironhorse1
                Using a 245 grain cast bullet with 7.6 grains of Unique has got to produce more pressure than a .357 using 7.7 grains of Unique with a 158 grain jacketed bullet.
                Normal operating pressure for 300 blackout cases/primers is around 60,000 PSI.
                Normal operating pressure for 357 magnum cases/primers is around 35,000 PSI.

                There really should be no problem with exceeding 35,000 PSI in a cartridge designed around a 60,000 PSI use.
                Randall Rausch

                AR work: www.ar15barrels.com
                Bolt actions: www.700barrels.com
                Foreign Semi Autos: www.akbarrels.com
                Barrel, sight and trigger work on most pistols and shotguns.
                Most work performed while-you-wait.

                Comment

                • #9
                  ER308
                  Member
                  • Jan 2013
                  • 135

                  Originally posted by Spaceghost
                  Does the the action cycle with these loads?
                  Tests were done with 16" bolt action. Model 7 action. I would think these would NOT cycle a gas gun. With fast pistol powder, pressure should be way too low by the time the bullet reaches the gas port.

                  Comment

                  • #10
                    ironhorse1
                    Senior Member
                    • Nov 2012
                    • 1004

                    First let me say I found your data to be of great interest as far as loading heavy lead bullets in the .300 blk.

                    Lots of good information for everyone to review. The math is just a way of seeing when one is getting the best use out of a particular powder. It does apply to all powder data.

                    Honestly I never stated that I thought your loads were over pressure.
                    It was just a heads up that there is a point when the next slower burn rate powder might be best.

                    When working up loads there are many factors to consider. One is case capacity. At 24 grains of water for the .300blk as opposed to 31 grains for the .223 there is less capacity. The .357 holds 27 grains and the .30 carbine 21.

                    Now there is a very heavy bullet to consider as well. All these things must be taken into account as loads are worked up to the desired levels of velocity and accuracy.

                    Without pressure testing the only way we can determine if we have exceeded specs is to measure the case web with a micrometer. A fired factory case will give the maximum case web expansion. Fired reloads which exceed the factory measurements will have increased pressure. That's old school as used by Ken Waters.

                    I'm happy that you got the results that you wanted. The chronograph data shows the sweet spot for subsonic up to 6.8 grains.

                    I also use Unique as do many others for 30-30 cast bullet loads. The case does have a greater capacity @ 45 grains of water and ten grains with a 180 cast GC bullet is a nice load.

                    So I never doubted your loads or data and it's been the best that I have seen for awhile.

                    irh

                    Comment

                    • #11
                      ER308
                      Member
                      • Jan 2013
                      • 135

                      additional data - 208 gr Hornady AMAX

                      Hornady 208 gr AMAX
                      COL: 2.27 no crimp
                      Ballistic coefficient: G7=0.325
                      Powder: Unique
                      CCI SRP
                      Rifle: AAC Micro 7 1:7" twist

                      gr pwdr/ velocity fps
                      6.2 / 1040
                      6.4 / 1075
                      6.6 / 1108

                      There were no signs of high pressure with any of these loads.

                      The 6.6 gr loading grouped best at 5 shots in 1.25" @ 100 yds.

                      JBM calculator gives the following:

                      distance yds / drop in. / velocity fps
                      50 / +2.4 / 1078
                      100 / ZERO / 1055
                      150 /-10.2 / 1037
                      200 / -28.4 / 1020
                      250 / -55.0 / 1006
                      300 / -90.2 / 992
                      350 / -134.2 / 979
                      400 / -187.3 / 966
                      450 / -249.7 / 954
                      500 / -321.6 / 942

                      Comment

                      Working...
                      UA-8071174-1