Exterior Ballistics

[JD338]

Here is an interesting read on exterior ballistics.
http://www.rathcoombe.net/sci-tech/ball ... thods.html

JD338

 

[onesonek]

That is interesting! One thing really suprised me. That being how much more the FailSafe's out penetrated the Barnes TSX. Likely due to the Barnes opening up slightly more, and possibly slightly faster.
Albeit, if I ever felt I needed something other than the Nosler Partition, I would likely go with the Swift A-Frame, looking at that info.

 

[Guy Miner]

Thanks! I skimmed it, will go back and read it in detail later. It's way beyond the casual penetration and expansion tests some of us have conducted.

Would tend to call it "Terminal Ballistics" instead of "Exterior Ballistics" though. Exterior ballistics is concerned with the flight of the bullet between the firearm and the target.

Terminal Ballistics is what happens when the bullet strikes the target.

Interior or Internal ballistics is concerned with the acceleration of the bullet inside the barrel.

Regards, Guy

 

[caribouhunter]

really interesting!
we can see that speed or heavy weight does not always equal deeper penetration.
the 150 scirocco i use in my 7 mm wsm did fairly well in the test.

 

[onesonek]

really interesting!
we can see that speed or heavy weight does not always equal deeper penetration.
the 150 scirocco i use in my 7 mm wsm did fairly well in the test.

That's true,,for the most part, it's terminal sectional density and how fast that shape takes form.
The faster a bullet expands, the faster it loses momentum. And then the weight retention, of course comes into play.
Take the cast also for instance. The intial sectional density is generally lower when compared to rifle bullets, and way slower also. But when cast or heat treated to bhn where they don't deform, they penetrate more. Commercial castor's, cast or heat treat hard hard, claiming it aids penetration. This is true in part, but their main reason, is so the bullets don't beat all to heck in shipping. One really don't need a bhn 22 at modest rifle, or mag pistol velocities. What I have read and confirmed with some limited testing, bullets slighty harder than 1 bhn per/100fps terminal veloctiy wont deform much. So I run mine 1 bhn roughly over muzzle, or like 15 bhn for something starting out at 1400 fps. Just in case I have to drive through hard heavy bone at 10 feet But then it also depends on what the barrel likes or wants.