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The Army's new Squad Automatic Rifle will be Chambered in .270 Win. ...ish.

Discussion in 'Rifle Country' started by Garandimal, Feb 1, 2019.

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  1. Texas10mm

    Texas10mm Member

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    The requirement is that is has to penetrate level IV body armor at 600 yards.
     
  2. MTMilitiaman

    MTMilitiaman Member

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    Another thing people need to consider is logistics. The SAW and the M27IAR are used to fill the automatic rifle role at the fire team level because they are light enough to be used by one man and because they take the same ammunition as the standard issue rifle. The IAR and the standard issue M249 can both even take the standard issue ammo in the standard issue magazine. So while I understand the limitations of the 5.56 is the support role, esp with regard to penetration and range, I also understand this is done because it is logistically expedient.
    Adding another weapon system and cartridge to the mix doesn't make a lot of sense from a logistical standpoint. It adds more complexity than performance. We are now talking about providing weapons, training, ammunition for three different cartridges--a standard issue rifle and infantry cartridge, a SAW specific round, and the standard issue support and LMG round. Each of these will have multiple types of ammunition that need to be fed to the front lines and make it to the right people, and the added complexity in doing this arguably outweighs the performance advantages.
    The new M80A1 features a 130 gr bullet @ 3100 fps from an M240. It reportedly has enough velocity to fragment reliably to almost a quarter of a mile and can defeat all current and projected body armor threats at that range from a system that is already fielded and logistically supported.
    I have been saying that a medium bore caliber is the best way to eliminate our dependence on two different infantry rounds. Done right, a 6.8mm cartridge could replace both the 5.56 and the 7.62 NATO cartridges. But this would be a massive logistical undertaking in peace time, to say nothing of having troops deployed and actively fighting in several different theaters. It doesn't seem like a practical time to do this, especially given all the systems, like the IAR, M855A1, and M80A1, that we have recently spent time and money testing and implementing.
    Like I said, I will believe it when I see it.
     
  3. MTMilitiaman

    MTMilitiaman Member

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    If you can get past the creepy robot-voiced narration:
     
  4. CoalTrain49

    CoalTrain49 Member

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    I'm waiting for huge lots of military surplus 5.56 x 45 to hit the civilian market.

    0.10/round should move it out pretty fast.:D
     
  5. CapnMac

    CapnMac Member

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    They actually did, 20 or 30 cases, actually.
    It was not so much the ±1.2e10 rounds of M2 Ball in inventory as the Depression had set in, and there was likely going to be no new money for the War Department to improve the range fans at all of the freshly-built ranges across CONUS.

    That, and MGs were still expected to be able to put 150-17gr ball ammo out to 2000-3000m and be effective.

    We in the present have the math & science to get a BC that might support a 120-130gr round out to 2km. Maybe. The question becomes one of will the weight offset help the weapons platoon guys better hump GPMGs.

    There's no real change in the logistics train for a new round. The trains still have to support bot h 5.56nato and 7.62nato for GPMGs, and certain volumes of .50bmg, depending upon the mix of who/what the trains support.
     
  6. Random 8

    Random 8 Member

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    Watched as much of the above video as I could handle. With the pressure specs they're looking at, it might be more feasible than we think to send a 135 gr bullet at 3000fps. They're looking at somewhere in the range of 80Kpsi if I heard and did the conversion correctly. You could probably push a 6.8 that would fit in the AR envelope that fast at that pressure.

    I found this, looks like the project has inertia. https://www.armytimes.com/news/your...oth-fire-this-more-accurate-and-deadly-round/ There's a link to the actual bid package if somebody is really hungry for alphabet soup, and if somebody knows how to navigate to the actual specs of the prototype ammunition to be submitted, I'm all ears. It may be classified, so don't get us in trouble.
     
    Last edited: Feb 3, 2019
  7. CapnMac

    CapnMac Member

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    Would be a long wait. Infantry will be toting 5.56nato for the foreseeable future.

    And, more importantly, DRMO no longer releases loaded ammo in any form. If the 5.56 is ever dropped (and entirely, meaning Reserves and NG units entire), might be a glut of pulled projos and empty cases, but that will be it. Historical note, California NG units were still using M2 Ball in BAR and 1919 MGs up to about 1978. So, if the 5.56 were mothballed today, there would liekly still be units using it in 2050 or 2075.
     
  8. CoalTrain49

    CoalTrain49 Member

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    That's too bad. I guess I'll just keep reloading.:D
     
  9. CapnMac

    CapnMac Member

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    Yeah, that's why you can find "reloaded LC" ammo about; it's all delinked MG ammo and pulled components bought in bulk (either hundredweight or ton, if I remember the adverts right).
     
  10. d2wing

    d2wing Member

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    I mentioned this today to a friend that shoots military matches. He told me that his buddy in the military told him they are testing a 6.5 caliber. So-o-o, one rumor is as good as another to me.
     
  11. MachIVshooter

    MachIVshooter Member

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    Short of .50 BMG AP, not a single round ever chambered in a shoulder fired rifle will do that. Not even the mighty .408 CheyTac. Level IV will stop .30-06 AP literally at the muzzle.
     
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  12. mshootnit

    mshootnit Member

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    This sums up my experience with both cartridges as deer hunting rounds, consider that you are comparing a 120 gr. bullet out of a 6.8 at 2500 fps muzzle against a 77 gr [email protected] 2700 fps muzzle
     
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  13. alsaqr

    alsaqr Member

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    An examination of how it got that way is in order. M855 ammo fired from the barrel of the M16A2 rifle was effective on unprotected personnel to 500 meters.

    Then the US Army:

    1. Sawed off the M16 barrel to 14.5 inches and called the gun the M4/M4A1. Result: Muzzle velocity was reduced.

    2. Sawed the barrel off again to 11.5 inches. In some cases the barrel was shortened to 10.3 inches. Result: Muzzle velocity was further reduced.

    3. Developed a new round, the M855A1 Enhanced Performance Round; the so called "green round", with a hardened steel penetrator and a copper slug. That bullet will penetrate 3/8 inch of mild streel plate at 300 meters.

    4. The M855 round generates about 52,000 psi when fired. The M855A1 round generates about 62,000 psi. That increase causes barrels to wear out faster; sometimes bolts break and bolt lugs shear. Years ago i obtained 200 rounds of M855A1 ammo. A friend loaded up ten rounds in his old Colt AR-15. The sixth round broke the bolt.

    5. The designer of the AR-15/M16 rifle is L. James Sullivan: He scaled down the AR-10 rifle designed by Stoner. Mr. Sullivan has recently re-designed some parts of the M4/M4A1 rifles in order to make them more durable.

    i'm a retired US Army M/Sgt. After the problems associated with the adoption of the M16 rifle, i'm not sure the Army will do the right thing.
     
    Last edited: Feb 4, 2019
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  14. Llama Bob

    Llama Bob Member

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    This has to be a science fair project and nothing more. The problems of running at those sorts of pressures are numerous and not easily solved. There's a reason no current small arms operate above 65 KPSI.
     
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  15. Slamfire

    Slamfire Member

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    I have commented many times on the clueless nature of Army Ordnance Bureau personnel. They are right up there with the group that investigated Bernie Madoff, three times, and never figured out that Madoff was running the largest Ponzi scheme in the history of the world.

    A good service rifle round operates in the lower 40 kpsia. I don't know if they still make student drivers sit through the old "Speed Kills" movies, but there ought to be a version for the Ordnance Corp. The slope of the pressure curve is exponential and when you start out with a 60 kpsia round, little changes in anything, be it temperature, aged ammunition, slightly different manufacturing tolerances, and rims gets pulled off and rounds stop extracting. The best service rounds were in the 40 kpsia range, when units were deployed to desert environments, their weapons worked, even when stored in vehicles. When the Army Ordnance Bureau "cooks" its people to 160 F in HMMWV's , because the vehicle is so over loaded that they can't fit an AC unit, and it is simpler to cook the occupants than fix the over weight problem, well the ammunition gets cooked with the people. And there is plenty of evidence the Army is having pressure problems with the current 5.56 ammunition in the Sandbox. You can hear of the design features they have had to adopt in M4's, because of the unreasonable pressures, one of which is a very long throat. They cut a long smooth bore section to reduce breech pressures. This is stupid and creates inaccuracy and a short barrel life.

    What the Ordnance Corp ought to do is buy well designed rifles and ammunition from the Chinese Military. An examination of the current Chinese round shows it is superior at all distances to the 5.56, and it operates in the lower 40 kpsia range. Just eyeball the round, lots of taper. Taper is good, the AI improved cartridges, which the 5.56 falls into that category, are too straight and finicky about feeding. They also drag on extraction. Straight cartridges don't steer or feed as well as ones with lots of taper and they drag on extraction. And then, the Chinese round has a nice thick rim. Makes it harder to rip the rim off under extraction. And those are first order, eye ball evaluations. I have no doubt going deeper would show even more good ideas with these Chinese rounds. If you don't know, China graduates vastly more Scientists and Engineers per year than the US, and more Chinese get Science and Engineering PhD's in US Colleges, than native born Americans!. The country has a lot of highly educated, intelligent people.

    Of course the US Ordnance Department wants a big expensive research program, call it white collar welfare, want to throw a lot of money down a rat hole, and don't want to adopt a well engineered foreign round and rifle system, because they can't admit there is someone out there with more technical expertise then themselves.

    Bbu89Am.jpg

    1gfvWmb.jpg
     
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  16. someguy2800

    someguy2800 Member

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    You've stated this several times before that 5.56 nato has less body taper than other us service rounds and it is still a false statement. I have drawn them out in solidworks myself to get the body angle from the top of the extractor groove to the base of the shoulder.

    6.5 creedmoor = .177 degrees
    30-06 Ackely improved = .257 degrees
    6.5 grendel = 2.99 degrees
    7.62 nato = .344 degrees
    30-06 = .469 degrees
    6.8 spc = .473 degrees
    5.56 nato = .497 degrees
    30 carbine = .518 degrees
    7.62x54r = 5.71 degrees
    7 and 8mm mauser = .659 degrees
    7.5x55 swiss = .703 degrees
    5.45x39 = .801 degrees
    50 BMG = .934 degrees
    chinese 5.8x42 = .936 degrees
    7.62x39 = 1.342 degrees

    PerryHubbling Feb. 04, 2019 12.28 PM.jpg
     
  17. Coal Dragger

    Coal Dragger Member

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    Never going to happen.
     
  18. Catpop

    Catpop Member

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    You forgot 3 very nice tapers
    218 bee
    22 savage hp
    Oh theyre too small
    And
    300 HH
    Oh yeah it’s too big
    Then there’s always the 275 HH
    And the two HHs already have their own belt!!!!!!
     
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  19. someguy2800

    someguy2800 Member

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    Well since you brought it up

    218 bee = .632 degrees
    22 savage = 1.300 degrees
    300 H&H = .817 degrees
     
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  20. Catpop

    Catpop Member

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    Gee thanks someguy2800
    HH- is that body taper without measuring belt?
     
  21. someguy2800

    someguy2800 Member

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    thats from just in front of the belt to the base of the neck
     
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  22. Jessesky

    Jessesky Member

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    I’m a bit confused on the 34 vs 42 post. The 42 was lighter than the 34 because the 34 had more milled steel parts and the 42 was stamped. Even so, both were within a couple pounds of eachother. I wouldn’t say they serve any different roles. Apart from the 34 having a better barrel change technique for confined spaces, and the 42 benefitted from cheap and fast manufacturing
     
    Last edited: Feb 4, 2019
  23. someguy2800

    someguy2800 Member

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    I could be wrong but I was under the impression that the mg34 was most often used in an offensive role with the ammo belt in the drum on the left side, allowing it to be carried and operated by one man with an assistant gunner acting as ammo carrier and reloader. The mg42 was issued with a tripod that the assistant gunner carried and their were dedicated ammo carries assigned to feed it, and were used primarily from fixed positions.

    So if that's the case they used the mg34 like we did the later m60 and the mg42 like we did the m1919.
     
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  24. FL-NC

    FL-NC Member

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    For all of its problems and "teething pains", the M4 carbine family is still about the best thing going for our guys taking care of business. I worked both in operational positions as well as an instructor and in R&D. No one wanted anything to do with the SCAR- we accepted the H version and it morphed into its own small family of weapons, but only because "higher" wouldn't entertain the idea of a carbine version of the SR25/MK11 series of rifles, at least not at the time. Outside of JSOC, the idea of adopting the 416 for the rest of SOF was a non-starter. I do find it very amusing that the USMC pulled a fast one and was able to get it into their inventory- and that chapter is just beginning. The 6.8 SPC? I served with the guys in the 90's who were the brain trust for the idea. I know others who opted to use it in the land of bad things. Did it perform? Yes. But there is something comforting about knowing that you can resupply your ammo from any NATO or coalition unit in theater- whether it is from stocks of ammo in storage, or in the field off of some other guys gear- not to mention repairing your weapons if needed, in most cases.
     
  25. Garandimal

    Garandimal Member

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    Thanks for tellin' me.

    Did you tell the Army as well...?

    :D




    GR
     
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