New Cartridge Developments and Implications for Dismounted Infantry Soldiers

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  • #31
    Gents,

    While I acknowledge the importance of projectile design, I think the weight, profile, and handling characteristics of the machinegun are more important. Using a constant-recoil operating system will increase hit probability drastically, and untrained soldiers need very little time with such a weapon to be effective with it, since it's pretty much an aim and shoot = hit procedure. I posted some about this before the forum was destroyed, with links to video of the Ultimax, KAC LMG, and Kp31 Suomi submachinegun. You simply have to experience the shooter bliss that firing these types of weapons is, as you can basically write your name with them. Well-trained soldiers are simply lethal with them, as the Finns proved in 1939-1940 against the Soviets.

    They were basically using a 9mm subgun in the capacity that we use SAW's in today, that is how effective constant recoil is, and they stacked bodies until guys had to be pulled off the front line because the psychological weight of how many humans they had killed was unbearable for them to sustain. Keep in mind that they were shooting 9mm at guys fully-kitted out in winter gear, and still had that effect. They were also in way more enclosed terrain than one would find in Afghanistan, but the effectiveness of that system is a matter of historical record.

    When you look at the recoil of the SAW or AK, it is not conducive at all to keeping even short controlled bursts on-target, unless you muscle the crap out of the gun and drive it hard. The M240 on a flex mount was very good, but then they got rid of the flex mounts and installed a new buffer in it, which basically made it feel like constant recoil when the buffer was new. I protested about losing the flex mount..until I shot the gun with the new buffer. You question if you have even fired when there is no felt recoil. The 240 was already a laser gun, but then it got even better. Notice that these features are what Joe loves, but hates the weight.

    Regardless of what high-power ammunition is used in an LMG, as long as it has a constant-recoil mechanism, a novice gunner will be able to keep almost all the rounds on-target, and multiple hits of even a mediocre projectile design will ventilate a human target quite destructively. When I think about the capabilities of a Multirole LMG with the ballistics of a 6.5 Swede, I get excited. If one were to compound that with a well-designed projectile that penetrates barriers and fragments in tissue, it would be all the merrier.

    I want to reiterate the role that LMG's and GPMG's play in Light Infantry tactics...it is a dominant one. Whenever small unit tactics are being discussed, we always talked about how the 7.62 machineguns represented 50-66% of the firepower of the whole platoon, or figures like that. A belt-fed weapon brings a decisive amount of firepower to any land force encounter, and is usually one of the most addressed components of planning when discussing the details of actual actions on the objective for deliberate attacks, raids, ambushes, defenses, and Immediate Action Drills.

    While the guns may not be as sexy as sniper rifles or good marksmen, when they talk, everyone listens. The art of machine-gunning is too often overlooked on the outside, but it is a noble and coveted position in the Infantry. I'm in favor of giving gunners a super-light gun that tracks easy, with a superior cartridge, that they can also fight in the streets with when necessary.

    LRRPF52

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    • BluntForceTrauma
      Administrator
      • Feb 2011
      • 3897

      #32
      Originally posted by stanc View Post
      I'm afraid you're in error, John.
      Thanks, Stan. I'm happy to be corrected in order to base opinions on the facts as they stand.

      John

      P.S. By the way, LRRPF52, I greatly appreciate your inside info and theory based on sound, on-the-ground observation.
      :: 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

        #33
        Originally posted by LRRPF52 View Post
        While I acknowledge the importance of projectile design, I think the weight, profile, and handling characteristics of the machinegun are more important.
        I agree, but we've been discussing projectile design because that's a vitally important part of what the thread is about -- new cartridge developments.

        Comment


        • #34
          I agree, but we've been discussing projectile design because that's a vitally important part of what the thread is about -- new cartridge developments.
          stanc,

          It's also essential to have a new cartridge if any hopes of replacing the 2 current US shoulder-fired belt-fed machineguns with a single platform will be realized. The fact that cartridge developments are what they are now is what I think makes this new Multi-Role LMG a greater possibility in the near future.

          If the KAC LMG receiver was oriented in a half-bullpup configuration like the FG42 or M60, it would allow more barrel length to get velocities closer to 2800 fps with 6mm-6.5 projectiles. I'm thinking of an entirely new true bullpup design, that uses a simple "nutsack" solution like we used on the SAW, since feed-source location is much more problematic on a bullpup when using a box-shaped, versus straight magazine behind the pistol grip. With a little pig less than the length of an M16A2, you could still have a 24" barrel length and the first truly ergonomic design for gunners.

          Every machinegun I have shot, carried, or played with almost always has horrible ergonomics with regard to: 1) firing hand interface, 2) cheek weld, 3) eye-height relationship to sights, 4) carrying interface, 5) Center of balance, and most Western GPMG's have no provisions for mounting a drum or box to feed the gun with in a maneuver or practical environment.

          The MG42, HK21, and PKM are exceptions to the lack of attached feed source, and several designs have been field-rigged for the M60 and M240, but they were not part of the Basic Inventory Items of the US GPMG's when I was in. They just expected the gunner to rely on his Assistant Gunner for supply of ammunition, after burning through a 50rd starter belt. I must tell you that is one vulnerable feeling when you're humping a 30lb hunk of steel. Compare that to some bugger-eater running around with a PKM and its attached 100rd/200rd/250rd ammo can.

          Is it starting to make more sense now when I say, this end of the equation is broken? It just shows how tough and tenacious our guys are, especially when you look at the ridiculous loads they carry versus anyone we've fought in that past 50 years, and the overwhelming combat successes the US has displayed in dismounted warfare. I say we give Joe a break and increase his firepower and maneuver capability in one sweep.

          LRRPF52

          Comment

          • bwaites
            Moderator
            • Mar 2011
            • 4445

            #35
            Originally posted by warped View Post
            Yep it is all in the math Bill, E=MV2/450400 (muzzle) but if we determine that we retain enough of that a BB would make it through a plate of 4" thick steel if it were moving at 28K fps
            10-4, I was being a little facetious when I mentioned the velocity issue. I was stirring the serious pot these gentlemen are cooking, because I don't believe the velocities discussed are sufficient for true hard armor AP capability.

            However, I'm wondering now if I can drive a 110 grain AP round at 2800 FPS if it will penetrate 1/2 steel, which has been my test medium so far. If so, I think that would get through hard armor as well.

            Going to have to give it a try!

            Comment

            • stanc
              Banned
              • Apr 2011
              • 3430

              #36
              LRRP,

              Sure, the characteristics you desire in a GPMG make a lot of sense. It's just that, other than saying I agree, there's not much more to say.

              Heck, after 6-7 years of discussion, we still can't even get an existing belt-fed LMG converted to 6.5 Grendel. How are we going to design -- let alone build -- a completely new weapon?

              Stan

              Comment


              • #37
                Bill,

                What do you think about the ballistic mannequin idea I talked about earlier in the thread? Do you know of any CPR mannequins that are unserviceable, looking for a new, loving "home"?

                Tony Williams,

                Have you ever done a weight analysis of 6.5x55 Swede with 140gr versus 7.62 NATO, assuming equal weight links?

                Stanc,

                Heck, after 6-7 years of discussion, we still can't even get an existing belt-fed LMG converted to 6.5 Grendel. How are we going to design -- let alone build -- a completely new weapon?
                I'm glad you asked...

                Re armor:



                LRRPF52

                Comment


                • #38
                  Guys,

                  We're 12 years into a new century, with a plethora of old weapons from the last century, with more capacity to envision, design, prototype, RDT&E, and market new products than anytime in history. Someone will meet current & future demands that are unsatisfactorily being met by the default inventory right now.

                  All I see is opportunity, which combined with the ability to share information like never before, should result in revolutionary developments that are long overdue.

                  The field is ripe boys...

                  LRRPF52

                  Comment

                  • stanc
                    Banned
                    • Apr 2011
                    • 3430

                    #39
                    Originally posted by LRRPF52 View Post
                    Have you ever done a weight analysis of 6.5x55 Swede with 140gr versus 7.62 NATO, assuming equal weight links?
                    I don't have precise weight for 6.5x55, but with a 140gr bullet, it has to be heavier (due to fatter, longer case) than the 7.62x51 w/147gr projectile (392gr).

                    So, if you're hoping for a weight reduction, ya ain't gonna get it by switching to 6.5x55.

                    Comment


                    • #40
                      stanc,

                      Not suggesting 6.5 Swede as a cartridge as I feel it's COAL is too long. I'm just interested since it has performance that I like, and there are existing military 140gr loads for it that can be used as a reference. Since it has a .480" base diameter versus the .476" for 7.62, it would be able to use the same links and provide a theoretical weight comparison. I'm not sure how much the extra 4mm in narrower neck brass will affect the weight between the two cases, but it doesn't matter for what we're looking at. Rough figures show 7.62 147gr weighing 700gr more per 100 rounds of ammo, which is only .1 pound more than the Swede based on bullet weight alone.

                      This would represent the top limit in weight for a new LMG cartridge, and would penalize the SAW gunners heavily, so I would steer away from it on those grounds as well.

                      LRRPF52

                      Comment

                      • stanc
                        Banned
                        • Apr 2011
                        • 3430

                        #41
                        Okay, I got the following reply from an acquaintance.
                        Seems it's much lighter than my logic said it ought to be...

                        So, using the book value (22.9 grams), 100 rds of linked 6.5x55 would weigh 0.54 lbs less than a belt of 7.62x51.
                        Last edited by stanc; 05-18-2011, 10:57 PM.

                        Comment


                        • #42
                          stanc,

                          I suspect something like a 6.5x47 Lapua on full auto would be a barrel burner, but that is the direction the performance objectives would most likely lead. If a Grendel could match 7.62 M80 out to distance, that would be great, but getting the projectiles to speed is the problem. I'm just anticipating those that will say that they have a certain perceived or real performance of M80 ball at 700m, 800m, 900m, that the Grendel clearly does not, as far as hard impact on target goes.

                          If the requirements were reduced to say that it equals 7.62 trajectory only, then there is probably some room past 600m to argue in favor of the 147 impacting certain targets vs. an undetermined mass-produced 6.5 round of lesser weight. That's why the 140gr 6.5 military bullets interest me. I would not want the x55 case length for the reasons stated previously.

                          It is interesting to note that the 6.5x55 Swede with 140gr Norma Spitzer probably weighs less than the 7.62x51 M80 with 147gr, given the differences in case dimensions. The Norma might have a lesser powder charge weight as well, since it doesn't take as much to get a 140gr going 2600fps from a tighter neck when compared with what it does to get a 147gr going over 2800fps, and the Swede needs a slower-burning powder to push that bullet with its long bearing surface.

                          LRRPF52

                          Comment


                          • #43
                            Gents,

                            There may be some prudence in separating bullet design from cartridge design. For example, the hype about the M855A1 suggests that it tends to put a hole in thicker steel than does the 7,62X51 M80 in some circumstances. We can go very small in bullet and cartridge size and get interesting results: http://www.cbjtech.com/sida.asp?sida=5_Downloads. The penetrator in this 6.5mm cartridge is a 4mm diameter tungsten rod.

                            These suggest that arbitrarily setting a bullet weight or caliber may lead us away from very interesting and possibly compelling solutions.

                            Comment


                            • #44
                              stanc,

                              I don't see a need to test the 6.5x55 Swede specifically, as long as we can get .260 Rem or 6.5x47 Lapua to duplicate the velocity with 140gr bullets we're interested in. I think those Swede's are somewhere in the neighborhood of 2600fps, so that is easily attainable since I get 2850fps with 130 VLD's right now from a 22" .260 AR10. 6.5BR would also be another one to look at. If it's easier to use a readily-available 6.5 Swede rifle with readily-available 140gr Swedish Mauser ammo, that could be helpful. I have several friends that own those rifles in Finland, as well as 7.62 NATO rifles and machineguns there, so we could possibly conduct those tests this summer and winter.

                              Otherwise, I need to try some of the 140gr military-compatible bullets that are available in my .260, and I'm having a hard time finding them. I'm neck-deep in a lot of other work right now, so any suggestions in the right direction would be great. I just checked Midway, but couldn't find any 140gr 6.5mm FMJ's. I wonder if we could locate a source for just the 140gr Swedish military projectiles, separate from the loaded cartridges.

                              Basically, I'm thinking of testing the 140's versus the M80 ball at 500m, 600m, and 700m on some common mediums. Then we could work backwards in bullet weights with 6.5's if the 140's prove superior to the 147gr 7.62 NATO, which may seem like a foregone conclusion, but should be done on an unbiased assumption, since results are what matters.

                              I want to combine thin metallic barriers simulating light-armored vehicle skin, with some type of semi-fluid medium behind them to demonstrate both armor-defeat capabilities and follow-on affects to tissue simulant. I think we'll be able to incorporate these tests into one of the various sniper training events there, or my shoot schedule here.

                              LRRPF52

                              Comment


                              • #45
                                JASmith,

                                That 6.5x25 is an answer to all my concealed carry dreams. I've been a big fan of the 7.62x25 for a long time, and have actually drawn out some 6.5x25 concepts, but was limited by COAL and lack of available mags. This eliminates all those obstacles. That will have profound effects on PDW/pistol and SMG's if adopted. That tungsten penetrator on the armor door is eye-opening, if factually-represented. That will also cut weight significantly for my summer guns when clothing is less and thinner. Wow. I've had plans to custom-build a 1911 with a modified frame that will take Cz-52 mags, but there is no need for that if I can get this. It will also make the Bizon with helical mag a totally new animal...should probably stop talking now...

                                This still presents us with some potential problems for a LMG though, since sabots don't have the same accuracy potential, as you will notice with the 10.2cm groups at 100m, and 17.8cm groups at 200m, unless one would be willing to seriously decrease hit probability at 400m and beyond. A sabot-based system might be acceptable for a belt-fed weapon if the accuracy spread were figured into the shot-dispersal benefits of traditional machine-gunning, which could be mitigated with constant recoil since the gunner can basically walk rounds onto target very quickly. Hmmmmm....

                                LRRPF52

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