The Firing Line Forums - View Single Post - Explain On-the-Fly Ballistic Coefficient Changes

TXAZ · July 5, 2020, 07:20 PM

Here's a hint your kindergarten teacher never told you:

*Nothing* in ballistics is linear. Air flow is both laminar and turbulent and the ratio and values change with speed, attitude and more than a dozen other variables.

In general, BC drops as speed drops.

As such, a single number for a BC is likely a 'best case': Hornady says the G1 on their 750 gr AMax is 1.05 (G1), but Brian Litz measured it at .991

In general, and that's more like 'much of the time' a BC is going to be higher at much higher speeds. Until you start chasing X-15 rocket planes, then the tertiary and quaternary effects take over and ballistics math as we commonly use it doesn't work any more.

But kudo's to your instructor, you found an excellent one.

July 5, 2020, 07:20 PM	#8
TXAZ Senior Member Join Date: September 5, 2010 Location: McMurdo Sound Texas Posts: 4,322	Here's a hint your kindergarten teacher never told you: Nothing in ballistics is linear. Air flow is both laminar and turbulent and the ratio and values change with speed, attitude and more than a dozen other variables. In general, BC drops as speed drops. As such, a single number for a BC is likely a 'best case': Hornady says the G1 on their 750 gr AMax is 1.05 (G1), but Brian Litz measured it at .991 In general, and that's more like 'much of the time' a BC is going to be higher at much higher speeds. Until you start chasing X-15 rocket planes, then the tertiary and quaternary effects take over and ballistics math as we commonly use it doesn't work any more. But kudo's to your instructor, you found an excellent one. __________________ Cave illos in guns et backhoes Last edited by TXAZ; July 5, 2020 at 07:29 PM.