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ballistic coefficient for RMR 3GH bullets

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  • #448979
    Lee
    Participant

      Has anyone calculated the bullet coefficient for these types of bullets (both the 69 and 75 grain)? Also, has anyone shot them out of an AR15? How were the results and at what distance?

      #449011
      SC
      Participant

        I am not certain of the exact BC but out to 500 yards, the 69 RMR shot pretty close to 69 SMK data that I used in Strelok. The results were hard to say how accurate the load is but with a 16″ AR, I was able to hit 100% on steel targets between 200-500 yards. The 500 yard target looked to be about 10″ X 15″, measuring with my mil reticle.

        #449487
        ftnspace
        Participant

          75 gr RMR 3GH LOT 2

          I plan to get data on paper for a G7 estimate on the 75 gr when time allows.

          16″ 1:7 twist medium contour barrel AR-15, 5.56x45mm NATO chamber, suppressed

          Load: (work up, be safe, etc.)
          LC 09 brass (1x fired, FL size, chamfer, debur, flash hole uniform; no annealing)
          CCI No. 41 primer
          23.8 gr Ramshot TAC
          2.255″ COAL (PMAG Gen M2/M3 magazine length)
          RMR 75 gr 3GH LOT 2
          10 rd Avg Vel. 2,610 fps (LabRadar)
          ES 32 fps (on progressive press)
          8 shot group 0.33 MOA (actual MOA, not iphy)

          Slightly flatter shooting than expected, but similar to SMK.

          Performed well in 5-10 mph winds on 66% sized steel out to 700 yards, although my red dot limits me to 450-500 yards for reliable unsupported hits.

          For the 69 gr RMR 3GH:

          I can’t get the 69 gr 3GH to shoot well for me with TAC or AA 2460 at all, but I have a slow and a fast sub MOA node for 69 SMK with AA 2460.

          I’ll try Shooter’s World AR Plus, which might be just the ticket.

          I have my doubts that AA 2520, Varget, IMR 4895, IMR 4064 or CFE 223 will work well if AA2460 doesn’t, as they’re all a bit slow for that bullet in my 16″ barrel but I’ll try them regardless.

          #450037
          Lee
          Participant

            If the ballistic coefficients are close to Sierra Matchkings 223, then the price of the RMR 3GH might be worth s try. I looked online and the SMK 69 grains and 75 grains are well over $100 plus for a box of 500.

            #453304
            John Winsor
            Participant

              I used a bc .335 when I shot the 69’s out to 600yds at a nra xtc match. The .335 bc held true for me.

              #459061
              augief16
              Participant

                John, amateur question I’m sure, but is that a G1, or G7? I’m guessing G1 but since this is the first time in my life I’m considering BC, who knows. Thanks!

                #459074
                SC
                Participant

                  @augied16

                  Yes, that is a G1 BC. I used .169 G7 when I was shooting the 69 RMR.

                  #459089
                  augief16
                  Participant

                    Terrific! Thanks for the timely reply. By chance any reliable BC info on the 75gn 3GH?

                    #459091
                    John Winsor
                    Participant

                      Hello, yes it’s the G1, I won’t be able to test the 75’s at 600 until next year. Winter is definitely here in Alaska.

                      #459096
                      SC
                      Participant

                        I have not had a chance to try the 75 3GH but Hornady uses a .395 G1 BC for their 75 BTHP. That’s where I would start.

                        Remember that posted BCs are an average because velocity affects BC. A lower velocity will yield a lower BC.

                        #459105
                        augief16
                        Participant

                          Much appreciated. Thanks!

                          #463396
                          texasrebel7508
                          Participant

                            If you have any of these left could you please tell me the length of the projectile? Are these the same length as the hornady 75 gr BTHP’s?

                            #463538
                            John Winsor
                            Participant

                              @texasrebel
                              75gr rmr is .952
                              75gr hornady bthp .982

                              #463540
                              John Winsor
                              Participant

                                Also Brian Litz from Berger bullets has tested the 75gr hornady bthp and he got a bc of .355

                                #470020
                                Jacob Wilcox
                                Keymaster

                                  The RMR 75 is about .355

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