Cavity Back 118gr gel results

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  • rickOshay
    Warrior
    • Apr 2012
    • 784

    Cavity Back 118gr gel results

    Hello Horde, sorry of the long delay. I finally got to the range to shoot the Cavity Back bullets into gels - that I loaded up in October.

    The 118 gr Cavity Back MKZ bullet measures 1.349" long and has a G1 coefficient listed at 0.530. The cavity is 0160" deep and holds about 0.8 gr CFE223.

    I weighed 10 as I pulled them from the box and they varied between 117.1 to 117.7 gr with an average of 117.3 with 4 of them weighing 117.2 None weighted 118 gr.

    Using the methods published in Chapter 6 - Terminal Ballistics in Vol 2 of the 6.5 Grendel Reloading Handbook here's what I got:




    Starting from Left:
    1789 fps, 23.5" penetration, 117.4 gr, expanded to 0.510"
    2165 fps, 25.0" penetration, 117.4 gr, expanded to 0.625"
    2433 fps, 22.0" penetration, 106.5 gr, expanded to 0.630"

    One petal on the third shot had broken off. The other two retained essentially 100% of their weight.

    At 2433 fps, the bullet entered the gel at left and opened up after 1⅜" penetration, then "propellered" through the gel. The fragments shown are from previous tests (NOT the CBB) and are sitting on top of the gel

    The permanent cavity is about 1.10" diameter for 5" then narrows to about 0.5-0.6".

    My findings agree well with those published by CBB: http://www.cavitybackbullets.com/category-s/114.htm

    This bullet opened up below 1800 fps, likely to be down in the high 1600s/low 1700s. Which is MUCH lower than the Barnes.

    Really exciting new bullet for the Grendel. I've got the 105 gr CBBs loaded up for next test. The 105 is only 1.246" long which may be better suited for mag length loading.


    See PredatorDown's range report on the 118gr..
    Finally had a chance to begin to put the 118gr Cavity Back Bullets through their paces at longer ranges. Overall, I was pretty impressed with them for being an all-copper bullet designed for hunting. Short version: Good -- as accurate as 123gr amax factory rounds (which in my rifle, are very accurate) Bad -- BC wasn't
    Last edited by rickOshay; 12-04-2016, 05:08 PM.
  • sneaky one
    Chieftain
    • Mar 2011
    • 3077

    #2
    Very nicely done. Is this all copper only, or is it a gilding metal , like the Gmx ?

    Comment

    • SDguy
      Warrior
      • Oct 2015
      • 367

      #3
      Thanks Rick

      Looking forward to the results with the lighter 105 GR CBB.

      Must admit I am a little concerned over petal shedding experience at the higher velocity. Fear this may not bode well for the lighter bullets.

      Hope my fears are proven wrong.

      Comment

      • rickOshay
        Warrior
        • Apr 2012
        • 784

        #4
        Originally posted by sneaky one View Post
        Very nicely done. Is this all copper only, or is it a gilding metal , like the Gmx ?
        CBB calls them "copper alloy" on their website.

        Comment

        • Kilco
          Chieftain
          • Jan 2016
          • 1201

          #5
          Holy crap.. better b.c than the 127 LRX. I'd give these a go in my 260 for sure.

          Comment

          • rickOshay
            Warrior
            • Apr 2012
            • 784

            #6
            The published BC has been questioned. See here: http://www.calguns.net
            Last edited by rickOshay; 12-28-2016, 07:24 PM.

            Comment

            • Cornbread
              Warrior
              • Dec 2015
              • 288

              #7
              They have the g1 listed at .505 on the website now.

              Comment

              • rickOshay
                Warrior
                • Apr 2012
                • 784

                #8
                Here's another view of the wound channel in the gel.

                Looking into the gel just under the path of the bullet. The point of impact is the dark spot just above the channel.

                Comment

                • CavityBackBullets
                  Bloodstained
                  • Nov 2016
                  • 98

                  #9
                  Thank you for the nice report rickOshay.
                  The projectiles are all copper with minimal other elements, above 99%. It is sourced from a specific region for the quality.
                  BC has been lowered to .505 after PredatorDown's 1000 yard test to fit in with his data.
                  I will always adjust BC to what real world results are once I see enough reliable data. It is what it is.

                  Interesting on the weights you got. I did not find that much difference in my checks and will look harder at that, thank you.

                  The 118 grain MKZ and the 105 grain MKZ are different a hardness. The 105 is designed to take more speed.
                  The one petal that sheared off is not something we see typically until over the speeds rated on the website by a bit.

                  Terminal performance has been impressive across all calibers and weights so far.
                  Massive blood loss
                  Exit wounds larger than expected for caliber

                  Comment

                  • rickOshay
                    Warrior
                    • Apr 2012
                    • 784

                    #10
                    Thanks CBB. Great to have your input. Change in BC noted.

                    Comment

                    • diddlyv
                      Warrior
                      • Aug 2016
                      • 352

                      #11
                      I received my CBB 105 and 118 last week have not had a chance to play with them. was going to post dimensions but Rick took care of that
                      Queen of Battle
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                      Life NRA, DAV ,VFW, SASS

                      Comment

                      • Beerswimmer
                        Warrior
                        • Dec 2015
                        • 130

                        #12
                        Thanks for the gel test! Ammo looks like a great option to me.

                        Is here ANY way I could persuade you to do a gel test with some Wolf 100gr?? There is only one test known, and it's from a loooong time ago.
                        UT ALII VIVANT !!!

                        Comment

                        • rickOshay
                          Warrior
                          • Apr 2012
                          • 784

                          #13
                          If you mean the Wolf steel case, I did shoot them into gels about a year ago.

                          See post #116. http://www.65grendel.com/forum/showt...-Part-2/page12

                          Please PM me if you want more info. Let's keep this thread on track.
                          Last edited by rickOshay; 12-06-2016, 12:09 PM.

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