Which cone?

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tjones96761
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Which cone?

Post by tjones96761 » Mon Dec 07, 2015 12:33 pm

Most pictures I see are like the one on the left, but in my mind the one on the right would "cut" the gas flow away from the center line better. Is it ease of machining, or actually better to have that flat nose like the one on the left? Is the flat nose just to debur the thru hole without chamfering the edge? Appreciate any input.

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fastfire
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Re: Which cone?

Post by fastfire » Mon Dec 07, 2015 1:01 pm

In my very limited experience in this I believe the first version causes more disturbance slowing gases.

propeine
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Re: Which cone?

Post by propeine » Mon Dec 07, 2015 1:56 pm

ignore

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daviscustom
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Re: Which cone?

Post by daviscustom » Mon Dec 07, 2015 2:58 pm

The drawback to the first one is you have no meat at the bore.....any erosion an you will immediately start enlarging the bore.
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sizulku
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Re: Which cone?

Post by sizulku » Mon Dec 07, 2015 3:56 pm

the second picture (with sharp edge/nose) will make inconsistent accuracy

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whiterussian1974
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Re: Which cone?

Post by whiterussian1974 » Mon Dec 07, 2015 4:04 pm

sizulku wrote:the second picture (with sharp edge/nose) will make inconsistent accuracy
...because of wavefront interference buffetting the bullet's shank. This causes wobble and inconsistant aerodynamics acting upon the nosecone after base is pushed off-center. Rendering gyroscopic instability.
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Capt. Link.
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Re: Which cone?

Post by Capt. Link. » Mon Dec 07, 2015 6:20 pm

tjones96761 wrote:Most pictures I see are like the one on the left, but in my mind the one on the right would "cut" the gas flow away from the center line better. Is it ease of machining, or actually better to have that flat nose like the one on the left? Is the flat nose just to debur the thru hole without chamfering the edge? Appreciate any input.
The edge thickness of design two will not impact the accuracy to any degree unless the bullets length is significantly shorter than the edge thickness of the baffle in which it passes through.Both will work fine in most any build.If you use #two I would add a flat of at least .025 to take the fine edge off .I normally use a short neck on my baffles with a undercut leaving a .050" edge at the top.It being a mix of design one and two.

You are correct that number two will cut away more gas than the first design while the larger flat on the first one will aid turbulence in low pressure builds.With either one just debur don't chamfer the inside edge.
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