New Cartridge Developments and Implications for Dismounted Infantry Soldiers

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  • stanc
    Banned
    • Apr 2011
    • 3430

    Originally posted by BluntForceTrauma View Post
    I don't see a military bullet having any trouble at all getting match bullet BC. The machines can swage or machine any nose profile you care to design.
    That would seem to be true, provided the bullets are the same weight. For instance, the BCs of the 150gr .308 Sierra FMJBT and MatchKing bullets are virtually the same at velocities over 1800 fps.

    However, IIRC discussions on Tony's MG&A forum, consensus was that a lead-free 6.5mm ball projectile would be limited to a maximum weight of ~110gr, due to length and stability factors. If the cited trade study looked at 123gr match bullets, there would be a substantial difference in BCs relative to a 100-110gr ball round.

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    • stanc
      Banned
      • Apr 2011
      • 3430

      Originally posted by Variable View Post
      What about heat management without the brass cartridge case?
      I'm not sure IIRC, but I think I read that there is less heat transfer through the plastic case to the chamber, thereby creating fewer heat issues than with brass cases? If my memory is faulty on that question, I trust someone will correct me.
      Also, how much more space does the larger diameter cartridges take up? Maybe not much, but they do appear fatter.

      Trading weight (great to reduce it!) for possible heat issues or too bulky ammo containers for number of rounds carried? I don't know squat about it, just wondering out loud....
      The LSAT 5.56mm cases are a little less than 0.5" diameter, ~20% fatter than brass cased 5.56 NATO, which would make the height and width of a 30-rd LSAT magazine comparable to a 30-rd 7.62 NATO or .45 ACP magazine. That might be a bit too bulky for some people's taste. (And keep in mind, 6.5mm CT rounds would be even fatter...)







      OTOH, because of the link dimensions, it appears that there would not be much difference in capacity for 5.56mm machine guns.

      Comment

      • Variable
        Chieftain
        • Mar 2011
        • 2403

        What are the upper row of belted cartridges in the last pic? They look considerably skinnier than the bottom row.

        Maybe for a rifle/carbine they could take advantage of the shorter overall cartridge length and use a P90 style of magazine. I don't know how the ergonomics would work out, but if possible it might be advantageous. Lying prone with a 50 round magazine full of a flat shooting 6.5 cartridge would be pretty cool.

        Maybe a P90 type mag underneath the bore. It'd shove sideways into a slot, and be ejected out the other side. The bolt would have longer travel (long recoil) and still bottom eject. The magazine slot would have a lever that ejects the mag out the opposite side from it's insertion. It could possibly be partially ambidextrous, by allowing a reversible catch system.

        Getting the mag under the barrel would eliminate the width problem for getting your head closer to centerline, and also get the optics closer to the boreline..... Just some more goofy out loud thoughts.
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        • stanc
          Banned
          • Apr 2011
          • 3430

          Originally posted by Variable View Post
          What are the upper row of belted cartridges in the last pic? They look considerably skinnier than the bottom row.
          The top row is caseless ammo. Which they've had much difficulty working out the bugs, so they decided to concentrate on the fatter, plastic-cased type at bottom of the photo.
          Maybe for a rifle/carbine they could take advantage of the shorter overall cartridge length and use a P90 style of magazine. I don't know how the ergonomics would work out, but if possible it might be advantageous. Lying prone with a 50 round magazine full of a flat shooting 6.5 cartridge would be pretty cool.

          Maybe a P90 type mag underneath the bore. It'd shove sideways into a slot, and be ejected out the other side. The bolt would have longer travel (long recoil) and still bottom eject. The magazine slot would have a lever that ejects the mag out the opposite side from it's insertion. It could possibly be partially ambidextrous, by allowing a reversible catch system.

          Getting the mag under the barrel would eliminate the width problem for getting your head closer to centerline, and also get the optics closer to the boreline..... Just some more goofy out loud thoughts.
          I really don't know if those ideas are definitely goofy, or potentially great. But so far, it looks they plan on a conventional weapon configuration.

          Comment

          • LRRPF52
            Super Moderator
            • Sep 2014
            • 8569

            Originally posted by stanc View Post
            I think it's great that they plan to develop 6.5mm CT ammo and carbine, but I fail to see how CT technology in any of the mentioned calibers is going to change the game, which is try to kill the other guy. AFAIK, the only real change CT promises is reduced weight. Otherwise it has the same limitations as weapons that fire conventional ammo.

            BTW, I can't help but wonder if the "Cartridge Optimization Trade Study" was based on 6.5mm Scenar or MatchKing projectiles, or realistic military bullet designs. If the calculations were done using the match bullet BC, the conclusions may be a bit optimistic.
            The CT case is more efficient at burning the propellant, and with the 5.56 versions, soldiers involved in the testing of it stated that they use the 200m stadia line for 300m impact, so velocity appears to have increased as well.

            The LSAT LMG also has a counter-recoiling operation that makes it so that not only is it more accurate and easier to shoot than the SAW, it also out-performs the M4 on the qual lanes. Since the cartridge length is significantly shorter, a soldier's basic loads increases dramatically, while also being lighter, even with a caliber increase over 5.56 NATO. Basically everything about it is a major positive and over-match over legacy systems.

            It also changes things in that the entire concept of our MTO&E gets turned on is head since you have a very lightweight system that can be used for everything a rifleman, SAW gunner, and DM do, as LSAT has select-fire capability. When the new KAC carbines were deadlined during the testing, the guys pulled the Leupold Mk.6 optics off them, and tried them on the LSAT using SEMI to engage targets out to 800m effectively.

            A 6.5mm LSAT with a .550 G1 or .265-.270 G7 projectile in 6.5mm would make the M240 and PKM obsolete.
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            Comment

            • LRRPF52
              Super Moderator
              • Sep 2014
              • 8569

              CT deals with heat much better than brass. Electron flow through a thick polymer is more difficult than a thin alloy, and the chamber is separate from the barrel with LSAT. It's a counter-rotating chamber that goes back and forth like an alternating revolver with a camming action.

              There is no longer the ogive and projectile length limitation associated with metallic cases. The projectile is seated inside the case fully, so there is no longer consideration for neck and shoulder location, because there is no neck or shoulder anymore. Projo length is now driven by case length and primer space.
              NRA Basic, Pistol, Rifle, Shotgun, RSO

              CCW, CQM, DM, Long Range Rifle Instructor

              6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

              www.AR15buildbox.com

              Comment

              • Variable
                Chieftain
                • Mar 2011
                • 2403

                Originally posted by stanc View Post
                The top row is caseless ammo. Which they've had much difficulty working out the bugs, so they decided to concentrate on the fatter, plastic-cased type at bottom of the photo.

                I really don't know if those ideas are definitely goofy, or potentially great. But so far, it looks they plan on a conventional weapon configuration.

                Okay thanks, and scratch my previous. I'm disregarding the top row (caseless) for now.

                I found this vid:



                That's helping me unscrew my head a little bit about how this thing works, and I can also see the "revolving chamber" in action. That was really tossing me for a loop. I couldn't picture it for the life of me. This is pretty neat--- if everything works as well as they say it does. No reason to disbelieve them, just healthy paranoia with anything involving government.LOL

                Your picture above..... It ejects behind the feed area? That looks like an ejection port over the trigger area? I see the other beltfed is a "pusher" with no rearward "extraction"..... How does the one above work???


                Heck, I'm still trying to wrap my marbles around the physics of the projectile being so deeply seated in the case. The base of the bullet is practically on the primer!

                I guess if you want to roll your own you'd need an injection mold for the cases!
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                We either hang together on this, or we'll certainly HANG separately.....

                Comment

                • Variable
                  Chieftain
                  • Mar 2011
                  • 2403

                  Originally posted by LRRPF52 View Post
                  CT deals with heat much better than brass. Electron flow through a thick polymer is more difficult than a thin alloy, and the chamber is separate from the barrel with LSAT. It's a counter-rotating chamber that goes back and forth like an alternating revolver with a camming action.

                  There is no longer the ogive and projectile length limitation associated with metallic cases. The projectile is seated inside the case fully, so there is no longer consideration for neck and shoulder location, because there is no neck or shoulder anymore. Projo length is now driven by case length and primer space.
                  That all just blows my mind! I look at an AR, and I've dinked with them so long that my brain just "sees" how they work. This new stuff will take a while (if ever) for me to actually intrinsically "get it".....

                  I'm not calling them liars, but it's hard for me to accept that it's accurate with a seperate moving chamber like that. If they say it is, then I know it must be, but that just seems so weird to me.
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                  • stanc
                    Banned
                    • Apr 2011
                    • 3430

                    Originally posted by LRRPF52 View Post
                    Since the cartridge length is significantly shorter, a soldier's basic loads increases dramatically, while also being lighter, even with a caliber increase over 5.56 NATO.
                    It looks to me like a 6.5mm version would require magazines of about the same width and (more importantly, in regard to handling/ergonomics) height as 30-rd 7.62x51 mags.



                    I suppose that drawback would be an acceptable tradeoff for the increased basic load, though.
                    It also changes things in that the entire concept of our MTO&E gets turned on is head since you have a very lightweight system that can be used for everything a rifleman, SAW gunner, and DM do, as LSAT has select-fire capability.
                    Surely you don't seriously think the military would give a belt-fed LMG to every infantryman?
                    A 6.5mm LSAT with a .550 G1 or .265-.270 G7 projectile in 6.5mm would make the M240 and PKM obsolete.
                    Perhaps. But how do you propose to achieve such a high BC if bullet weight is in the 100-110gr range? The 107gr MatchKing only has a 0.406-0.420 BC, depending on velocity, and I doubt that would be improved upon with a lead-free, ball round.

                    Comment

                    • stanc
                      Banned
                      • Apr 2011
                      • 3430

                      Originally posted by Variable View Post
                      Your picture above..... It ejects behind the feed area? That looks like an ejection port over the trigger area? I see the other beltfed is a "pusher" with no rearward "extraction"..... How does the one above work???
                      It does look like an ejection port. I've no idea how it works, though.

                      Comment

                      • stanc
                        Banned
                        • Apr 2011
                        • 3430

                        Originally posted by Variable View Post
                        I'm not calling them liars, but it's hard for me to accept that it's accurate with a seperate moving chamber like that. If they say it is, then I know it must be, but that just seems so weird to me.
                        Yeah. I'm wondering just what all is wrong with it. I mean, I have to think it has one or more problems we're not privy to.

                        Otherwise, if it's as marvelous as we're being told, why hasn't it been adopted and fielded, already?

                        Comment

                        • Variable
                          Chieftain
                          • Mar 2011
                          • 2403

                          Originally posted by stanc View Post
                          Yeah. I'm wondering just what all is wrong with it. I mean, I have to think it has one or more problems we're not privy to.

                          Otherwise, if it's as marvelous as we're being told, why hasn't it been adopted and fielded, already?
                          The glass is half full portion of me hopes it's because it really is that awesome, and they're just proving to themselves that it is. No surpises or embarrassments that way.

                          I wonder about chamber alignment with the barrel and stuff like that. The chamber rotates left to fire, does it ever get crudded up and not align perfectly with the bore? Stuff like that.

                          If it's as good as they say, then I'd love to see it fielded.

                          Since the ammo is plastic instead of brass, I wonder if they can crank out more of it faster and cheaper? Heck, I'd like to see a civilian release. Hopefully the plastic used is very long term stabil. I've got WWII ammo that's still good to go.

                          I wish I were CIC for a day or more. I'd ban "green" consideration from projectile construction, and seek legislation forever forbidding such BS from even being a tiny thought related to our ammo.
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                          We either hang together on this, or we'll certainly HANG separately.....

                          Comment

                          • cory
                            Chieftain
                            • Jun 2012
                            • 2985

                            Originally posted by Variable View Post
                            That all just blows my mind! I look at an AR, and I've dinked with them so long that my brain just "sees" how they work. This new stuff will take a while (if ever) for me to actually intrinsically "get it".....

                            I'm not calling them liars, but it's hard for me to accept that it's accurate with a seperate moving chamber like that. If they say it is, then I know it must be, but that just seems so weird to me.
                            Of course it's more accurate. They're using essentially custom hand loaded ammunition vs military rounds that have a 2 moa (I think it's 2) requirement in an M4. I do hope it works as well as they say it does.

                            However, I do have my doubts. Watching that video I see a couple of places in the mechanism that could cause significant jamming if everything doesnt work properly. I have serious doubts on the decreased maintenance time. I don't see how caseless ammunition doesn't leave the chamber area absolutely filthy. But with that rotating chamber it could be much easier to clean than the current one.

                            Originally posted by stanc View Post
                            ...Surely you don't seriously think the military would give a belt-fed LMG to every infantryman?

                            Perhaps. But how do you propose to achieve such a high BC if bullet weight is in the 100-110gr range? The 107gr MatchKing only has a 0.406-0.420 BC, depending on velocity, and I doubt that would be improved upon with a lead-free, ball round.
                            I don't think he meant that platform, but the caseless ammunition technology.

                            You're still living in the AR15 world buddy. With caseleess ammunition why would we be subjected to a 115gr limit?
                            "Those who sacrifice liberty for security, deserve neither." Benjamin Franklin

                            Comment

                            • JASmith
                              Chieftain
                              • Sep 2014
                              • 1620

                              Originally posted by cory View Post
                              ...With caseless ammunition why would we be subjected to a 115gr limit?
                              Good point!

                              Also, a couple of earlier posts observed good velocities.

                              The added velocity is not necessarily a result of greater pressure or improved burn profiles even though I think the latter is indeed a factor.

                              I remember seeing the hype about how the ultra fat cartridges had better velocities for the same pressures as their full-length forebears. A little work with QuickLoad shows that the velocity enhancement in those cartridges is completely explained by the longer bullet travel for the same nominal barrel length. A shorter cartridge means that the bullet base starts out closer to the breech face, so it has to go further for a barrel whose length is defined as the distance from the breech face to the muzzle.

                              That difference could explain part of the velocity increase with telescoped ammunition.
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                              • BluntForceTrauma
                                Administrator
                                • Feb 2011
                                • 3897

                                I'm not really happy with the quality of our defense procurement these days. (If they were so good, we'd have had something like the 6.5 Grendel adopted already; doesn't need to be named the 6.5 Grendel, but needs to have an intermediate case with a high BC bullet. But, hell, why NOT the 6.5 Grendel, is my thinking?)

                                So I'm skeptical. Show me. Show me how the F-35 fighter is cooler than anything the Russians have or the Chinese might conceivably develop. The Russians just displayed a whole slew of armored vehicles in their May Day parade which I wouldn't want to face. (Bearing in mind that it's easy to either overestimate the threat capability when it's time to get funds from Congress, or to underestimate the threat capability when the budget is tight and we have to pretend what we have is state-of-the-art.)

                                But I digress and it's easy for me to go full rant mode. My point is, after the XM8 fiasco (rifle, not light tank — although that's another topic), I'm very much wait-and-see. Every new concept seems cool until you, literally, drag it through the mud.
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