THIS Is the Dedicated 65G Bullet I Want, Part 2

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  • stanc
    Banned
    • Apr 2011
    • 3430

    #76
    Originally posted by bwaites View Post
    I hope we can get a 90 above .400, but it takes a 75 grain VLD to get there at .224, and a 90 grain 6mm VLD to get above it , so I have great doubts!
    Me, too.

    110gr Barnes solid ---- 0.452
    100gr Lapua Scenar -- 0.424
    103gr GS Custom ----- 0.454
    95gr GS Custom ------ 0.424

    I just don't see the proposed 90gr bullet having BC higher than maybe 0.395, at best. And that's if it's a scaled-down Barnes .308 TAC-TX per John's concept. If it's a Hornady GMX or Nosler E-Tip, I'd expect significantly lower.

    That being said, I think the choice of 90 grains (or possibly even lighter weight) is preferable to the original 100 grains, at least insofar as a submission to Barnes is concerned. They already offer a 100gr TTSX, and might be reluctant to consider making another TTSX of the same weight.

    Hornady and Nosler are somewhat a different matter, though. Since the GMX and E-Tips currently marketed weigh 120 grains, they may entertain a lightweight monometal bullet up to 100 grains.
    Last edited by stanc; 10-25-2014, 03:44 AM.

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    • Bigfoot
      Bloodstained
      • Sep 2014
      • 36

      #77
      Originally posted by cory View Post
      What's the minimum velocity of expansion for those bullets? I suspect it's 2000+ fps. That's significantly higher than what we seek.
      Barnes claims 1800 fps but you're right, they don't open much at that speed and 2000 is more like it.

      But I fail to see your main point.

      From my 260 I'd guess max velocity would be 3400 fps, 400 less than the 80 gr TTSX from a 25-06. So the 400-500 fps difference in min. expansion is offset by the lower starting velocity.

      Besides I see it as a lower recoil load than a 243 that my kids and I could shoot at any distance. And I wouldn't launch it any faster than 3100 fps cause at that velocity the trajectory perfectly matches my scope and at 3100 the maximum range is 790 yds (.400 BC) to 880 yds (.450 BC) which is still almost twice the distance that I'll need.

      Originally posted by stanc View Post
      I just don't see the proposed 90gr bullet having a BC higher than maybe 0.395, at best. And that's if it's a scaled-down Berger .308 TAC-TX per John's concept. If it's a Hornady GMX or Nosler E-Tip, I'd expect significantly lower.
      You might want to edit that, oops too late.

      Try the exact profile of Bergers 6.5mm 130 VLD, with a sharp tip instead of an OTM and a couple grooves.

      As you know, Barnes makes the TAC-TX.
      Last edited by Bigfoot; 10-25-2014, 03:56 AM.

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      • stanc
        Banned
        • Apr 2011
        • 3430

        #78
        Originally posted by Bigfoot View Post
        You might want to edit that, oops too late.

        As you know, Barnes makes the TAC-TX.
        Yeah. Fixed it. Thanks.

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        • cory
          Chieftain
          • Jun 2012
          • 2985

          #79
          Originally posted by Bigfoot View Post
          Barnes claims 1800 fps but you're right, they don't open much at that speed and 2000 is more like it.

          But I fail to see your main point.

          From my 260 I'd guess max velocity would be 3400 fps, 400 less than the 80 gr TTSX from a 25-06. So the 400-500 fps difference in min. expansion is offset by the lower starting velocity.

          Besides I see it as a lower recoil load than a 243 that my kids and I could shoot at any distance. And I wouldn't launch it any faster than 3100 fps cause at that velocity the trajectory perfectly matches my scope and at 3100 the maximum range is 790 yds (.400 BC) to 880 yds (.450 BC) which is still almost twice the distance that I'll need...
          It's physics, a bullet opening can be talked in terms on Kinetic Energy. It's a little more complicated than that, but it simplifies things for our purposes. We'll also use the 100gr TTSX for this purpose.

          We know that the 100gr TTSX opens reliably down to 2000 fps (28570 ft lbfs) and holds together at all velocities in the Grendel Range, other than a few outliers.

          We want a solid that opens at 1600 fps, for the 100gr TTSX that's 18290 ft lbfs. However testing shows it doesn't expand at all at that velocity. You can change this one of two ways (I know of). You can change the composition of the material to weaken it or you can change the design to weaken it (opening up the hollow tip, giving it thinner walls) so that it'll require less energy to open it.

          If you do either of these you'll most certainly lower the maximum velocity at which it'll hold together. You'll have to lower the maximum energy level it can withstand roughly 10,000 ft lbfs. Nothing is free in life and nothing is free in physics.
          "Those who sacrifice liberty for security, deserve neither." Benjamin Franklin

          Comment

          • Variable
            Chieftain
            • Mar 2011
            • 2403

            #80
            Frankly there are at least two sides at odds here.

            One side uses longer barrels and wants real high velocity for hitting deer at relatively short ranges, and the other side wants a bullet that'd be ideal in short tubes (SBR), have low opening velocities, and maybe a "multi-role" capability.

            At least that's what it looks like to me from out here in the cheap seats.
            Life member NRA, SAF, GOA, WVSRPA (and VFW). Also member WVCDL. Join NOW!!!!!
            We either hang together on this, or we'll certainly HANG separately.....

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            • stanc
              Banned
              • Apr 2011
              • 3430

              #81
              Originally posted by Variable View Post
              Frankly there are at least two sides at odds here.

              One side uses longer barrels and wants real high velocity for hitting deer at relatively short ranges, and the other side wants a bullet that'd be ideal in short tubes (SBR), have low opening velocities, and maybe a "multi-role" capability.

              At least that's what it looks like to me from out here in the cheap seats.
              I agree. So I guess that makes the question: Will one bullet design be suitable for both missions?

              If the answer is no, then I suspect the SBR/low expansion velocity/multi-role proponents may be left out in the cold...
              Last edited by stanc; 10-25-2014, 04:43 PM.

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              • BluntForceTrauma
                Administrator
                • Feb 2011
                • 3897

                #82
                I envision this bullet being used for hunting medium game in 12- to 20-inch barrels out to 500 yards. It's raison d'etre is to use high velocity and high BC to minimize ranging and windage errors and yet with its monometal construction it still holds together to penetrate to the vitals, despite it being on the lighter side of traditional 6.5mm projectiles.

                Cory has a valid concern, and that technical challenge needs to be addressed. I do not think weakening the material is the way to reduce the expansion threshold; I want either 100% copper or 95% copper/5% zinc alloy, and I lean toward the latter. This leaves playing with the tip; I've suggested "pre-" enlarging the hollow point and capping it with plastic to maintain BC. While we wait for actual testing of these in gel, does anyone have examples of monometals holding together, even at extreme velocities?

                And that concern is mostly for the bigger 6.5s that might pick up the bullet for their use. I don't think 65G velocities will ever put a monometal in danger of disintegrating, even if designed for 1.5x expansion down to 1500 fps and a maximum 2x expansion at all velocities.

                As has been mentioned, no one bullet can be all things to all people, but, again, I think it fills a niche in the wide spectrum of 6.5mm choices.
                :: 6.5 GRENDEL Deer and Targets :: 6mmARC Targets and Varmints and Deer :: 22 ARC Varmints and Targets

                :: I Drank the Water :: Revelation 21:6 ::

                Comment

                • BluntForceTrauma
                  Administrator
                  • Feb 2011
                  • 3897

                  #83
                  Ran a JBM Ballistics chart of a 6.5 90gr at 0.400 BC and 2,800 fps.
                  Attached Files
                  :: 6.5 GRENDEL Deer and Targets :: 6mmARC Targets and Varmints and Deer :: 22 ARC Varmints and Targets

                  :: I Drank the Water :: Revelation 21:6 ::

                  Comment

                  • Bigfoot
                    Bloodstained
                    • Sep 2014
                    • 36

                    #84
                    JBM closely matches my Load From A Disk software. I didn't run it through Quick Load.

                    Since your 500 yd goal is easily surpassed you might lessen the BC with a shorter nose to increase powder space and velocity and/or increase the minimum velocity expansion to make it tougher.

                    The former would optimize performance in the 65G, the latter would help sales for the midcapacity 6.5s making it a more feasible bullet to manufacture.

                    Lookin good.
                    Last edited by Bigfoot; 10-25-2014, 07:52 PM.

                    Comment

                    • stanc
                      Banned
                      • Apr 2011
                      • 3430

                      #85
                      I wonder how it would do if launched from Variable's 10.5-inch barrel?

                      Comment

                      • BluntForceTrauma
                        Administrator
                        • Feb 2011
                        • 3897

                        #86
                        There's a technical reason and a selfish reason for keeping a 7mm tip. Well, I guess both are technical. Should I say practical vs. daydreaming? I still want a big tip for low expansion, but I also want to "reserve" the big tip design as a test bed that is easily converted to other tips. That's probably not a good reason, I suppose, because anyone wanting an M855A1 analog in 6.5mm certainly doesn't need my help. I just thought it might help for proof of concept. You'd be amazed how some big decisions actually get made from seemingly insignificant things. For example, it's quite possible the whole M16 thing really got started with General LeMay shooting watermelons with it in the backyard. Don't know if that's apocryphal, or not, but you know what I mean.

                        As I run ballistics of a 90 at 0.400 vs. a 123 at 0.510 I'm still very pleased with the heavier bullets in the 65G. The 123 is still a damn good combination and the winddrift, impact energy, and impact velocity is still hard to beat with any bullet of lower BC.

                        More anectodal data. My keywords in Google/Images were "barnes bullets high velocity impact."
                        :: 6.5 GRENDEL Deer and Targets :: 6mmARC Targets and Varmints and Deer :: 22 ARC Varmints and Targets

                        :: I Drank the Water :: Revelation 21:6 ::

                        Comment

                        • stanc
                          Banned
                          • Apr 2011
                          • 3430

                          #87
                          Originally posted by HANKA View Post
                          There's a technical reason and a selfish reason for keeping a 7mm tip. I still want a big tip for low expansion, but I also want to "reserve" the big tip design as a test bed that is easily converted to other tips. That's probably not a good reason, I suppose, because anyone wanting an M855A1 analog in 6.5mm certainly doesn't need my help. I just thought it might help for proof of concept.
                          How would it accomplish that, John. Please elaborate on what way(s) you think it'd help prove the concept.

                          Comment

                          • BluntForceTrauma
                            Administrator
                            • Feb 2011
                            • 3897

                            #88
                            Stan, if we had a body of data on the 90gr hunting bullet that I propose, velocities and external ballistics, etc., and if a military entity wanted to start with that bullet as a testbed and swap out the polymer tip and replace with a hardened steel tip, then their testing would be that much farther down the road because not only do they NOT need to design a bullet from the ground up, but they've got a known quantity that helps eliminates some of the innumerable variables. Not a big deal, but it helps, and sometimes that's all that's needed to get the ball rolling.
                            :: 6.5 GRENDEL Deer and Targets :: 6mmARC Targets and Varmints and Deer :: 22 ARC Varmints and Targets

                            :: I Drank the Water :: Revelation 21:6 ::

                            Comment

                            • cory
                              Chieftain
                              • Jun 2012
                              • 2985

                              #89
                              That's ironic for the same military reasons you want a 90gr bullet, I want a 100gr-110gr bullet. I really think the troops would be best served with a military bullet in the 105gr-115gr range from a Grendel.

                              If they're only switching to a 90gr 6.5mm, then why not stay with the 5.56 and load more 77gr smks??? It doesn't look good on charts. Now a 110gr to 115gr and 120gr to 130gr bullets compared to the 62gr and 77gr bullets of the 5.56 is a lot more appealing.
                              "Those who sacrifice liberty for security, deserve neither." Benjamin Franklin

                              Comment

                              • stanc
                                Banned
                                • Apr 2011
                                • 3430

                                #90
                                Originally posted by cory View Post
                                That's ironic for the same military reasons you want a 90gr bullet, I want a 100gr-110gr bullet. I really think the troops would be best served with a military bullet in the 105gr-115gr range from a Grendel.
                                Based upon what information? Is there any test data that shows which weight is optimal?
                                If they're only switching to a 90gr 6.5mm, then why not stay with the 5.56 and load more 77gr smks???
                                The 77gr SMK has a lead core. Western armies are switching to lead-free bullets weighing 62gr.
                                Last edited by stanc; 10-25-2014, 11:03 PM.

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