The Truncated Cone

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  • Last Post 26 May 2020
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cove posted this 25 May 2020

I am in the process of designing a bullet for a 30 cal breech seated wildcat and cannot decide on the configuration of the nose.  The specs will be sent to Accurate, so it will have a 0.18" meplat.  I like the looks of a nose with a radius, but am aware of the success of the truncated cone. Examples being the Eagan MX-4 30 ARD and it copies.  I was wondering if the truncated cone is successful because there is less mass in the unsupported nose. How about BC? They seem to do OK at distance. Any comments? 

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RicinYakima posted this 25 May 2020

IMHO, it is shock wave over the nose, and airflow subsonic. Supersonic it should not make a difference. Subsonic, airflow over the radius nose will provide more stability. The question is, will your bullet ever drop into the transonic range at the distances you shoot?

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Ross Smith posted this 25 May 2020

I shoot the Mx4 30ard in my 308x1.625 at 2020fps. The mold is an original Eagan. That's 30grn Varget(my load-my risk). It does well cast in linotype. The 14 twist in my rifle is the limiting factor. 

What is your cartridge dimensions? I won't steal it.(well maybe) Are you going to have a tapered ,long, throat like the Ardito designs?

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cove posted this 26 May 2020

Ross-The cartridge is a 300Whisp-R Improved. A Mike Bellm/David White concoction. See "Shooting A Wimp" in TFS#254.  Feel free to steal it.  At present I am shooting a 200 grain bullet at around 1250 fps, so I am sure it goes subsonic at at some point.  Racin-Yakima comment concerning stability at subsonic velocities was just the information I was looking for.  I am going for a nose with a radius. Thanks guys. 

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