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Old April 1st, 2009, 08:57 AM #1
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Dimpled Bullets??

Anyone seen this?

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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.
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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.
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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. “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.”
http://accurateshooter.wordpress.com...impled-bullet/
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Old April 1st, 2009, 09:05 AM #2
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If accuracy is acceptable, these would be a hoot.

With regards to pressures vs velocity, Barnes has several designs that can be driven faster due to driving band design reducing the contact area.

Berger's ballistician mentioned in the article, Bryan Litz, posts over at LongRangeHunting.Com and at BenchrestCentral.
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Old April 1st, 2009, 09:12 AM #3
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It's a golf ball!
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Old April 1st, 2009, 09:27 AM #4
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So we're taking up a collection to buy Ed a couple of boxes so we can get a test, right?
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Old April 1st, 2009, 09:55 AM #5
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Interesting idea, not sure what this would do to rotational stability since the bearing surface area is reduced. Would be nice if they talked about how much it raised the BC of their .308 projectile. If its on the same order of magnitude as the increase of the Cd, then Im going home and wacking a bunch of dents in my SMKs

If rotational stability is retained, shouldn't accuracy be the same if not better? Its been a while since I took fluid dynamics, but I think that having a turbulent boundary layer would would allow the bullet to "resist" slight changes in pressure, such as wind.
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Old April 1st, 2009, 09:57 AM #6
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I wonder if it'll be possible to fire a slice or hook.
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Old April 1st, 2009, 10:34 AM #7
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Quote:
Originally Posted by IDriveB5 View Post
Interesting idea, not sure what this would do to rotational stability since the bearing surface area is reduced.
Rotational stability is independent of surface contact, since it is a product of gyroscopic (inertial) action, which can take place within a sealed container with no loss of effect.
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Would be nice if they talked about how much it raised the BC of their .308 projectile. If its on the same order of magnitude as the increase of the Cd, then Im going home and wacking a bunch of dents in my SMKs
BC is inversely proportional to Cd, but I don't know what the numerical relationship is. Just saying it's 1:1, an increase in BD by .04 is substantial. The 175 SMK has a BC of about .495, so this would represent 8%, IF it is 1:1.
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If rotational stability is retained, shouldn't accuracy be the same if not better?
There are plenty of very stable bullets that are not accurate - pick anything that is light for the caliber and reduce QC. Accuracy is a product of uniformity with regard to balance, center of gravity vs center of mass and the base area must be uniform as to not leave the bore in a random direction.
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Its been a while since I took fluid dynamics, but I think that having a turbulent boundary layer would would allow the bullet to "resist" slight changes in pressure, such as wind.
Reducing wind drift would be a huge plus.
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Stop calling anti-gun politicians “stupid”. They are not. If you simply look at the way they conduct themselves, you can understand why they fear and hate armed citizens and the grave risk citizens present to the increasingly corrupt. The assault on gun owners and the Constitution/BoR has nothing to do with street-level crime and you will not “educate them” your way out of this.

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Old April 1st, 2009, 05:56 PM #8
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I smell an April 1 story here...
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Old April 1st, 2009, 08:22 PM #9
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Quote:
Originally Posted by BeltBuckle View Post
I smell an April 1 story here...
Those bullets are specially made for snipe hunting . . .

Actually I think this is legit, this is not the first time I've heard of this and I know who Bryan Litz is.
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Stop calling anti-gun politicians “stupid”. They are not. If you simply look at the way they conduct themselves, you can understand why they fear and hate armed citizens and the grave risk citizens present to the increasingly corrupt. The assault on gun owners and the Constitution/BoR has nothing to do with street-level crime and you will not “educate them” your way out of this.

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Old April 1st, 2009, 08:41 PM #10
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if anyone wants, i'll swing by and dimple up your automobile to improve the aerodynamics of the ride and improve gas mileage...
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