The Army Test New Long Range Bullet

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by jwp475, Apr 5, 2009.

  1. jwp475

    jwp475 Well-Known Member

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    U.S. Army Team Tests Radical New Dimpled Bullet « AccurateShooter.com Bulletin

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    At the U.S. Army’s Aberdeen Proving Ground, a team of ballistics technicians, supported by some of the U.S. Army’s top sniper instructors, has been quietly developing a radical new “dimpled” bullet. The exterior of the bullet resembles the dimpled surface of a golf ball. The function of the special dimpled skin is to reduce projectile drag, providing a flatter long-range trajectory, and greater retained energy at the target.

    .338 Projectile with MIM Exo-Jacket
    (3D-CAD Artist’s Rendering)

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    In their pursuit of a lower-drag bullet, the Army tried a variety of designs, including bullets with circumferential drive bands, dual-radius ogives, and rebated boat-tails. The dimpled “golf-ball” design was considered a “long shot” according to the design team, but it has performed beyond all expectations. The nominal drag coefficient (Cd) has improved by about +.040, while cartridge muzzle velocity has increased by nearly 80+ fps because the bullet’s dimpled skin reduces in-barrel friction. What’s more — the terminal performance of the dimpled bullet has been “spectacular”. The Aberdeen team set out to produce a slightly more slippery bullet for U.S. Army snipers. What they ended up with is a bullet with dramatically enhanced long-range ballistics and superior killing power on “soft targets”.

    Lt. Col. Ben Eldrick, Long-Range Projectile Project (LRPP) team leader, told AccurateShooter.com how the radical bullet was conceived: “During our initial design work, we wanted the benefits of a high-BC, pointed bullet, but in a design that could be mass-produced and could work as a tracer. We consulted some of the top civilian bullet experts, including ballistician Bryan Litz of Berger Bullets. Mr. Litz really got the ball rolling. He suggested that the ‘next big step’ in bullet design would involve the turbulent boundary layer over the body of the bullet. Litz told us that ‘pointing bullet tips will take you only so far… think about optimizing the airflow over the entire bullet’. That made a lot of sense to us. When you design a race car to be aerodynamic, you sculpt the whole body, not just the front bumper.”

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    Lt. Col. Eldrick continued: “It turns out Litz was right on the money. By employing a golf-ball type dimpled surface, we were able to optimize the turbulent boundary layer on the bullet body. This reduced the low-pressure wake zone behind the bullet significantly, resulting in reduced base drag. As a result the bullet experiences much less overall drag, effectively raising the BC.” The Army team had discovered that what works for golf balls also works for bullets.

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    After testing a series of prototypes, the Aberdeen bullet design team settled on a copper-jacketed bullet with dimples about 0.5 mm in diameter. The first-generation bullets were formed in special binary impact swages that press-form the dimples after the bullets were pointed up in conventional dies. Future production bullets will be made with an advanced metal-injection-molding (MIM) process that forms the dimples directly into the surface of the bullets. Rather than simply wrap the core material (which is classified), the MIM is molecularly bonded to the core. The Aberdeen LRPP team calls this “Exo-Jacket” construction, as in “Exo-Skeleton”.

    Higher Velocities Achieved

    There was a surprise benefit of the dimpled bullet design — higher muzzle velocities. Given the same powder charge, dimpled bullets exit the muzzle faster because they produce less in-barrel friction than do conventional bullets. This is because the recessed dimples effectively reduce the metal-on-metal bearing surface. Lt. Col. Eldrick revealed: “the added velocity was an unexpected bonus. With equal-pressure loads, dimpled .308 bullets will fly about 80 fps faster than normal .308 bullets. With the large .338-caliber projectiles, the difference is even greater… we can pick up nearly 150 fps.” Given the observed velocity gains achieved with dimpled bullets, Aberdeen designers are now working on dimpled shell casings for larger artillery projectiles.

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    Dimpled Jacket Delivers ‘Explosive’ Fragmentation

    While the internal design and core materials of the new dimpled bullet remain classified, the design team revealed that the terminal performance of the new bullet has been “spectacular”. The bullet penetrates like a FMJ but then explosively fragments, resulting in a devastating energy release in the target. According to Capt. Jack Sarazen, an Aberdeen engineer, “the enhanced terminal performance of the dimpled bullet was unanticipated. This was a serendipitous effect of the slight thinning of the jacket material where the dimples are pressed.” Sarazen explained: “Most FMJ bullets break along the cannelure and then fragment into two or three large pieces. With the dimpled bullets, you have multiple fragmentation points so the bullet literally blows up like a grenade in the target.”
     
  2. ICANHITHIMMAN

    ICANHITHIMMAN Well-Known Member

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    WOW thats cool I hope it works out for them.
     

  3. Michael Eichele

    Michael Eichele Well-Known Member

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    Very interesting read. Thanks for sharing.

    It will be interesting to see if this becomes a new trend and if so, if it will outlast other trends and become standard for VLD type LR bullets. It definatly could have potential! If the +.040 increase of BC is true, imagine what will become of the 300+ grain 338 bullets.
     
  4. Autorotate

    Autorotate Well-Known Member

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    I believe that article and it's posting to be APRIL FOOLS:)
     
  5. Eaglet

    Eaglet Well-Known Member

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    jwp475,

    That's mighty interesting. Surely wakes you up! :)
     
  6. canyonman1

    canyonman1 Well-Known Member

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    I've actually been thinking about that same concept for a few years now. Talked to Dave Corbin about it a couple years ago. Makes perfect sense to me. Seems I read something a while back that made those guys at Jet Propulsion Laboratory and NASA think so to.gun)
     
  7. bwaites

    bwaites Well-Known Member

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    I'm not sure how much boundary layer has at supersonic speeds. Seems like jet fighters, rockets, etc would all be benefitted by dimples if this actually was the case.

    It works with golf balls because they have a backspin, not sure how that would work with a bullet. Increasing the air pressure along one side of the bullet would wreak havoc with accuracy.

    I love the fact it quotes someone popular here on the boards, a spokesman for Berger, to increase its legitimacy.

    I'm calling "Sidd Finch"!

    Bill
     
  8. BountyHunter

    BountyHunter Writers Guild

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    Check the date that article was posted on 6mmbr. Hint= 1 April. :D

    Paul put three zingers up that has everyone hopping.

    BH
     
  9. britz

    britz Well-Known Member

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    This one has been going around for a while. pretty funny stuff. over on 6br there was discussion about them possibly helping subsonic projectiles???

    The army actually was messing around with the idea of creating dimples on projectiles back in the early '40's. A scientist was given the task of developing a bomb to blow up damns and they realized that dropping a sphere from a plane at low level was the ticket. They found that the gulf ball dimples was the ideal surface to ensure the bomb skipped on the water properly and stayed on target... however they ended up just using drum bombs with backspin if memory serves. They skipped the dimples because it was too hard to manufacture the dimpled shell at the time.
     
  10. grizlywinkleman

    grizlywinkleman Well-Known Member

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    cool stuff!
     
  11. rustycj8

    rustycj8 Member

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    I have been shooting them for years... as long as there's no water or sand traps around they work pretty well.:D
     
  12. Tiff

    Tiff Active Member

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    Hi britz I'm guessing your referring to Sir Barnes Wallis an English scientist....His most famous cylindrical bombs were used in operation Chastise, AKA 'The Dam Busters'.
    He also designed the 'Highball' bombs that are dimpled, much like modern golf balls/the basis of this article. More info here:
    Bouncing bomb - Wikipedia, the free encyclopedia

    Barnes Wallis - Wikipedia, the free encyclopedia

    Operation Chastise - Wikipedia, the free encyclopedia
     
  13. blipelt

    blipelt Well-Known Member

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    Nasa????? Are they the same scientist's who believe in climate change? The same one who helped come up with carbon credits? The same who's bank account in directly related to the topic?

    Hypothesis: an educated guess

    Being educated I would rather be experienced.


    Brent
     
  14. Iron Worker

    Iron Worker Well-Known Member

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    Just received my 80 gr Berger VLDs . What did I do with my center punch ? I'm gonna start banging on my bullets. I'll post the results tomorrow