BC effects from full value wind?

[Rhovee]

Question for the BC experts. Calculating a bullets BC is not a difficult task. The primary reason i choose a bullet is it's ability to not be kicked around in the wind. But how does the shape of the bullet not effect a full value wind (9 or 3 O'clock)? This would be very hard to measure BC this way. I have heard from multiple bench rest shooters that they see bullets fight the wind better even though on a chart it wouldn't. Examples would be the 105 VLD VS 115 VLD and 215 Hybrid VS 230 Hybrid. These don't have huge BC advantages over each other on paper when velocity is factored in. But on paper at 1K it is very obvious that MOA dialed for correct wind is drastically different than what charts say.

 

[bigngreen]

https://bergerbullets.com/form-factors-a-useful-analysis-tool/

 

[Rhovee]

There she is.

 

[Mikecr]

Calculating a bullets BC is not a difficult task.

Says someone who has never done it. Otherwise you'd know that the best you can do on paper is predict drag components summed to form factor for BC. From there field testing is needed to validate/adjust the numbers -always.
Much of this aerodynamics approach is born within racing and rocket sciences, and it's difficult even with ample resources.

how does the shape of the bullet not effect a full value wind (9 or 3 O'clock)?

Bullet shape absolutely affects drift in wind. Shape affects drag, which leads to lag, a primary component with wind drift.

BC is ultimately useful for drag and time of flight to target. There is no need for separate wind BC/drop BC considerations with free falling bullets.
Where observed wind drifts are out of line with calculations, the input numbers are wrong, or deficient with other ballistic attributes, like spin drift, or near -vs- far wind.
And 115gr bullets require higher spin than 105gr bullets, so this could lead to apparent discrepancies if not accounted for.

 

[Rum Man]

https://bergerbullets.com/form-factors-a-useful-analysis-tool/

Thanks for Sharing !

Rum Man

 

[ballisticxlr]

Says someone who has never done it.

Yes. OP, please post the mathematics that you're using to calculate a BC. I would be extremely interested.

 

[Rhovee]

Your right. I don't calculate BC. I was just suggesting that you can use muzzle velocity and drops to check an inflated BC. I have just heard of people getting better wind deflections from bullets than what is suggested by the bc.