GOLF BALL EFFECT?

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  • Last Post 15 February 2022
cove posted this 11 February 2022

The other day as I was floundering through the WEB (I am far from being able to surf), I came upon a jacketed bullet called "Geco Hexagon" (sounds like a six sided lizard).  These bullets have 6 longitudinal grooves along the nose and the claim is that these grooves produce a golf ball effect which enhances the BC.  That statement made me think of the Lapua 32 cal WCs which also have longitudinal grooves along the nose. The Lapua WC is noted for it's superb accuracy and I was wondering if the grooves are a contributing factor?  If so, it is going to be quite a challenge to produce molds with longitudinal grooves. What do you think?

 

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John Carlson posted this 11 February 2022

The dimples on a golf ball influence the airflow around it.  Backspin gives it aerodynamic lift so it flies farther.  Horizontal spin will cause it to curve left or right (I have researched this part extensivelyfrown).  Not sure how those grooves would apply aerodynamic lift but they could change the drag coefficient and therefore the BC.

John Carlson. CBA Director of Military Competition.

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cove posted this 11 February 2022

 In the original post I forgot to mention that all bullets have longitudinal grooves due to the rifling.  Spindrift's comment about the Geco Hexagon and the Lapua's reputation lead me to believe these bullets may have an advantage.  I also like John  Forrest's comment on knurling. Would knurling the nose of a WC be the the same as dimples on a golf ball? I have a knurling machine and will try it this summer and let you know what I find.

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Ken Campbell Iowa posted this 13 February 2022

John Forrest ... good eye ...

the indents in the Lapua bullet above don't extend out of the nose .. so the indents weren't formed by simple protrusions in the swaging die.   ( unless a good whack with the punch-out rod. ) 

so ::  moveable indentors in a compound die ?? ... or rolled in with a 2nd op ( a blade knurler ... ) ... 

******

one question is >> why not formed in a ribbed swage die in the first place ...  ? ...   guessing they didn't shoot as well ? ...   or maybe they were just ugly in the marketplace ...

i gotta get my Akkrit rifle together ..  and answer my own questions ...

ken

how about a segment of a rifle barrel to swage a bullet ?? ... a 2 inch long chunk, leave the rifled nose and relieve the lower half to groove/throat diameter.   would a swage made from a Lilja barrel be more accurate ?? ...

 

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John Carlson posted this 14 February 2022

Maybe it's the same folks who make fishing lures.  Don't have to know anything about fish, just have to know about fishermen.

John Carlson. CBA Director of Military Competition.

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RicinYakima posted this 11 February 2022

Golf ball effect is for spin perpendicular to the horizon, i.e. making the ball go farer. Since the bullet is spinning the grooves will give left to right motion. I think the Lapua is a manufacturing mark for the fixture aligning the bullet to the case during  loading. Nice marketing ploy though. 

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Ken Campbell Iowa posted this 11 February 2022

... i have been thinking about that Lapua bullet for a while ...  a little awkward for a mold ... but not so much for a swage die ... which is probably why Lapua used it ...

if i ever build an Akkrit rifle, i will make a swage for that design ...  i have hesitated as i don't want to be expelled from the range by envious fellow shooters for cheating ...  i guess i could just shoot my groups from standing ...

ken

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Spindrift posted this 11 February 2022

I have shot those Geco Hexagon 180grs bullets in a .35 Whelen, and can vouch for the accuracy potential. They are the most accurate jacketed bullet I’ve tried in this rifle.

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JohnForrest posted this 11 February 2022

How about adding the dimples to bullets like they knurl a knob

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Squid Boy posted this 13 February 2022

It would be my guess that if there was such a development in the surface of a bullet that could increase range and accuracy, we would have seen it already in military cannon ammo and most certainly in specialty sniper ammo. They have the need and funding to support that type of research. I am not sure if anything that worked in a cannon could scaled down to rifle sized bullets anyway. Just my two cents. Squid Boy

"Squid Pro Quo"

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Ross Smith posted this 15 February 2022

If dimples would help a bullet, then we would all be shooting ugly wrinkled bullets.

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Squid Boy posted this 15 February 2022

Looking more closely at the GECO bullet it would seem to me that those grooves offer channels for gas to escape. They do go around part of the curve in the ogive so the end would not be blocked off. Doesn't make a lot of sense to me. Thanks, Squid Boy

"Squid Pro Quo"

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