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Is the 5.56 history? Will the 6.8 Rem replace it?

Discussion in 'Rifle Country' started by Hokkmike, Mar 8, 2006.

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  1. Hokkmike

    Hokkmike Member

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    (By Chuck Hawks)

    The inadequacies of the 5.56mm NATO as a service rifle cartridge are well documented and have inspired many suggestions regarding possible replacements (some on this web site). Apparently someone in the U.S. Special Operations Command also realized the need for a more potent round and initiated work on a new cartridge designed to work in the M16 action.

    The new .270 caliber (6.8mm) cartridge is the result of at least a two year cooperative effort between Special Operations, the Army Marksmanship Unit, and Remington. Various calibers from .22 to .30 were tested before settling on a standard .277" diameter bullet, the same bullet diameter made famous in the .270 Winchester.

    Remington is offering four 6.8mm SPC factory loads, all with 115 grain bullets. These include two target loads, a Core-Lokt Ultra hunting load, and a Metal Case military-type load. No varmint load is included. The four factory loads all have a muzzle velocity (MV) of 2800 fps and a muzzle energy (ME) of 2002 ft. lbs. from a 24" test barrel. At 100 yards the metal case bullet (BC .325) has a remaining velocity of 2523 fps and energy of 1625 ft. lbs. At 200 yards the velocity is 2262 fps and the energy 1307 ft. lbs. And at 300 yards the velocity is 2017 fps and the remaining energy 1039 ft. lbs. These figures are taken from Remington's 2004 catalog.

    The trajectory of the metal case bullet looks like this: +1.2" at 50 yards, +2.7" at 100 yards, + 2.8" at 150 yards, +1.4" at 200 yards, -3" at 267 yards, and -6.6" at 300 yards. The maximum point blank range (+/- 3") is thus 267 yards. These figures are computed for a rifle with a telescopic sight mounted 1.5" over the bore. This, just like the Army claimed, is similar to the trajectory of the .308 with a 150 grain bullet.

    The lighter weight .277" varmint and hunting bullets will presumably be the most popular choices in the 6.8mm SPC, and the latter are not thick on the ground. Suggested examples include the 90 grain Speer HP varmint bullet, 100 grain Barnes X-Bullet, 115 grain Sierra HPBT, 115 grain Remington Core-Lokt Ultra, and 120 grain Barnes X-Bullet.

    (from another source)

    It would appear that military operators would have good reason to have confidence in the 6.8x43mm SPC. According to noted gunwriter Gary Paul Johnston, "For military purposes, the 6.8mm SPC outshoots anything in its class--including the 5.45x39mm, 5.8x43mm [Chinese Army's standard infantry rifle cartridge], 7.62x39mm, and even the 6.5mm Grendel. Producing increased incapacitation at all ranges out to 600+ yards, the 6.8mm round fires a 115-grain Hornady Match or Sierra Match .270 caliber bullet at over 2600 fps (feet per second) from a 16-inch barrel M16 type rifle called the Mk-12 Variant "Recce", and has essentially the same trjectory as the M118 7.62mm NATO Match cartridge. A conceptual 6.8mm SPC version of the Special Purpose Rifle (SPR) also exists. The 6.8mm SPC is at least as accurate as the 5.56mm NATO and 7.62mm NATO rounds now used by U.S. Military Forces." (November 2004 Issue of "Guns & Weapons for Law Enforcement" Magazine, p.62).
     
  2. pauli

    pauli Member

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    /me makes popcorn
     
  3. High Planes Drifter

    High Planes Drifter Member

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    I scincerely doubt it; at least anytime in the foreseable future.
     
  4. jd25q

    jd25q Member

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    The problem with the 6.8mm is the bullets have low sectional densities and low ballistics coefficients. They are very light in the .270 line. Both of these qualities hurt long range performance.
     
  5. cgv69

    cgv69 Member

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    At this point, its a pretty safe bet that the 6.8 will not dethrone the 5.56, at least for the military.

    I would be highly shocked to see any new round for the military until they decide to replace the current platform. Even then, most of the weapons they have seriously looked at have all been 5.56 based
     
  6. USSR

    USSR Member

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    Short answer -- Nope. Much as I would like to see a heavier caliber replacement for the 5.56, the 6.8 Rem is DOA.

    Don
     
  7. Bartholomew Roberts

    Bartholomew Roberts Moderator Emeritus

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    You can also do a search here and get considerably better information on the 6.8SPC than that article.
     
  8. Zak Smith

    Zak Smith Moderator Emeritus

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    Welcome to 2004.
     
  9. Bobarino

    Bobarino member

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    i'd think the 6.5 Grendel is gaining more ground than the 6.8SPC. even Wolf is making the 6.5 now. its long range ballistics are WAY batter than 6.8. i don't think either one will replace 5.56 in the next ten years anyway. i still say .260 remington is the way to go. light, already proven, (against game anyway) plenty of range, tooling already exists, light recoil. but then that wouldn't allow the .gov to waste a gazillion tax payer dollars developing their own goofy proprietary cartridge that costs a ton. silly me.

    Bobby
     
  10. Jack19

    Jack19 Member

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    No, 5.56 isn't doomed. (Actually it works pretty well in it's niche.) And it's unlikely that 6.8 will replace it.
     
  11. rbernie
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    rbernie Member

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    I'm sold - where can I go to mail-order a 6.5 Grendel barrel and bolt for an upper that I'm building?
     
  12. Bobarino

    Bobarino member

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  13. rbernie
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    rbernie Member

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    Alexander the leader? Heck, they invented the 6.5 Grendel and then kept the cartridge (and uppers and bolts and such) proprietary for over two years. I decided several years ago not to pay for one of their pre-assembled uppers, which is why I'm not currently shooting the 6.5 Grendel.

    In recent past, Alexander has reputedly provided certain other vendors with chamber reamers, and authorized additional sources to supply brass and barrels and such. Given your posts, I thought that you were 'in the know' on this and had sources of supply lined up for third-party (affordable) 6.5 Grendel bits.

    Sorry for the confusion.
     
  14. TexasRifleman

    TexasRifleman Moderator Emeritus

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    This sounds just like the "10mm will replace the .45" spin when that great round first appeared. There may have been many technical reasons why 10mm was superior to .45, but you just can't supplant one of the most used calibers in the world with a few technical changes and some new gear.
     
  15. Zak Smith

    Zak Smith Moderator Emeritus

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    Anyone familiar with development of the SPC knows this is not true.
     
  16. Bobarino

    Bobarino member

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    i know, i was being sarcastic.

    i'm affraid i don't have any more information on the 6.5 than your average googler. sorry to dissapoint.

    Bobby
     
  17. Dr.Rob

    Dr.Rob Moderator Staff Member

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    The Army killed the 6mm option the FIRST (that I know of) time in the early 80's with the development of the SAW (now the M-249), due in part to cross-comapatibility with other NATO nations.

    While we can arguably bring our own pop-gun (pistol) to a fight we might have to share rifle ammo with our allies.

    Just a thought.
     
  18. carnaby

    carnaby Member

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    I keep seeing the term "cross section density" used. I don't understand what this means. Anyone care to explain? Which cross-section does it refer to, looking at the bullet nose-on, or looking at its side? :confused:

    And how does this change with bullet shape anyway? Aren't the bullets basically made out of lead and have the same density thoughout, except for the jacket? :confused:
     
  19. Mute

    Mute Member

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    The 6.8 SPC was not conceived as a general replacement for the 5.56. Some units that had access to the shorter barrel ARs found the 5.56 lacking and wanted something that could resolve that problem without having to replace the existing firearms. After a great deal of research, they settled on the 6.8 SPC. It was the answer to a very narrowly defined problem and it did that quite well. The 6.5 and the 6.8 both have certain qualities that will be beneficial for certain needs. Neither cartridge were competing to be a replacement for the 5.56 either then or now. Edited due to Forum Rule #3 - BR
     
  20. KriegHund

    KriegHund Member

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    It should.

    But it wont. Not anytime soon, anyways.

    I dunno, they ARE switching from 9mm to .45. So maybe there is hope.
     
  21. longhorngunman

    longhorngunman Member

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    Why would you want to replace the 5.56 Nato? It works great for what it was designed for. Remember it's being used on human beings mostly not some tough hided strong animal. Need greater distance, that's what the DMR is for.
     
  22. USSR

    USSR Member

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    That's the problem. Design something for one set of parameters, and then along comes a different kind of war with a 'nother set of parameters.

    Don
     
  23. KC&97TA

    KC&97TA Member

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    cough, cough (I never said this)

    Rumor on the 'cool side of the house' says that the guys who have reason for a .45 or 6mm may so be equiped on a wider scale in the future. Riflemen may get thier A4's replaced with a 6mm. The various test .308's are on the streets, shorter shottys, and various 'new toys' are getting to were they need to go. With the demise of the Corps DET-1 we'll have to wait and see where the Kimbers will end up and there's a screeming for more .45's in a hurry.

    This distribution has been on a "who rates" so those in the rear with the gear, will keep thier M16A2's and 9mm.

    Not everyone is switching to .45acp, just those who NEED it and will USE it

    5.56 doesn't do well killing humans when they're doped up on Coke/Heroin-coctail of suicidal intentions
     
  24. longhorngunman

    longhorngunman Member

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    Neither will .308 on that scenario.
     
  25. berettashotgun

    berettashotgun Member

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    I work for OC-ALC and in one of my many classes on the warfighter I was shocked to hear that troops killed in action have less of a death benefit than a civ fed employee (me). The instructor, retired AF, was disgusted to state this fact. Quote," Where's the outrage?" I think that applies to anyone recieving anything but the best tool for the job in combat. .45's ( or at least .40's) and 260's minimun.
     
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