# Ballistics for Excel Forum

Title: BfX now contains drag function for 9/16 inch spheres
Post by: admin on May 05, 2011, 12:28:10 AM
I have included a drag function "GS" for 9/16 inch spheres. To be used for shotfgun ballistics. Use it with BC=1 in every formula.

Later I will update BfX in order to provide a way for calculating the drag for other sized spheres.

Robert
Title: Re: BfX now contains drag function for 9/16 inch spheres
Post by: ThunderDownUnder on May 06, 2011, 02:07:17 AM
Amazing stuff Robert! I have always thought of shot and shotguns as being ultra close range. What will the longer ranges be that require calculations that include spherical BC?

IanP
Title: Re: BfX now contains drag function for 9/16 inch spheres
Post by: admin on May 06, 2011, 09:31:11 AM
Ian,

there is a BfX user (mman) who wants to calculate shotgun properties. Did so before. On his request I put GS in. As it turns out the ballistics of spheres is more complicate to calculate than our sigar shaped ones. The issue here is that the drag properties these bullets, for sizes that are relevant for hunters, black powder and clay shooters do not scale in a simple way with physical dimensions. Something called the Reynold number plays a role - something I merely touched 30 years ago  in my physics career.  I am still studying the subject and may be BC=1 is a premature statement, hence I cannot really answer your question.

mman?

Title: Re: BfX now contains drag function for 9/16 inch spheres
Post by: mman on May 06, 2011, 10:36:02 AM
Quote from: ThunderDownUnder on May 06, 2011, 02:07:17 AM
Amazing stuff Robert! I have always thought of shot and shotguns as being ultra close range. What will the longer ranges be that require calculations that include spherical BC?

IanP

Max effective range of shotgun is a sum of many factors. It depends on shot size, shot material and how tight the pattern is. Size of the target plays also a big role in that. In some cases 100 - 150 meters is longest range where shotgun is still useful and effective. Novadays high muzzle velocities (aprx. 500 m/s) and high density (high bc) shot are available for shotgun handloader. It is not usually a problem to get enough hitting power to kill game far longer distances than 100 meters but in many cases it is hard to get pattern that is tight enough for that.

Goal of shotgun ballistic calculation is also a bit different than it is with rifle. Most of the time I use my shotgun ballistics calculator to determine best shot size for ammunition and current application. Max effective range for current ammuntion is also interesting to know. So it is almost always the terminal velocity that counts. Of cource it is possible to calculate also trajectories but often there is no interest to that.

And Robert, thanks for the GS drag function..
Title: Re: BfX now contains drag function for 9/16 inch spheres
Post by: ThunderDownUnder on May 07, 2011, 12:03:11 AM
mman,

Thanks for posting the info on what you use spherical BC for and why its useful. I found what you are doing very interesting and using BfX to determine the best shot size is a yet another practical use for the functions!

Ian