Muzzle Energy Formula

[Wadman]

Anyone know what it is? Also, what's the formula for computing sectional density?

Buff, thanks. Writing it down this time so I don't lose it.

[ June 28, 2001: Message edited by: Wadman ]

[BUFF]

Muzzle energy is obtained by multiplying the square of the velocity (in feet per seconds) by the weight of the bullet in grains and dividing by 450,000.

Sectional density is obtained by dividing the bullet's weight in pounds (7,000 grains in a pound, so a 147 grain bullet weighs 0.021 pounds) by the square of it's diameter in inches.

[ June 28, 2001: Message edited by: BUFF ]

[EMDII]

KE = [M(V-squared)]/2 (thanks!)

- Typical BC for .30 MilSpec is around 0.387
- SD is related to exterior and terminal ballistics. You want a high SD for in-flight (exterior) ballistics. The depleted uranium long-rod penetrator (LRP) of the M1 tank 120mm gun has a VERY high SD on the order of 3. The SD of a typical .308 is 0.221.

Low SD is preferable inside the barrel (interior ballistics). This has the result of presenting a large piston to the expanding gas, accelerating the projectile quickly. Once you are exterior, high SD minimizes drag. In the case of the SABOT round, it also maximizes forces present as the round attempts (usually successfully and terminally) to penetrate the target.

[ June 28, 2001: Message edited by: EMDII ]

[Southern Raider]

Slight correction:

Kinetic Energy = 0.5 * mass * velocity^2

In English units, mass is in slugs and I cannot confirm how many grains are in a slug.

[DanB35]

Originally posted by Southern Raider:
<STRONG>In English units, mass is in slugs and I cannot confirm how many grains are in a slug.</STRONG>

It's 7000 grains to the pound, and ~32.16 pounds to the slug, so ~225120 grains/slug.

[doubletap]

For determining muzzle energy why not use the old Dean Grennel formula, it is quick, easy to remember, and typically accurate to a couple of foot pounds.

bullet weigth(in grains) divided by the constant 225218, times muzzle velocity, times muzzle velocity, divided by 2. works every time.

Doubletap

[K. Funk]

I haven't heard the term "slug" as applies to physics for years. Hats off to you mad ballistic physicists.

krf

[BUFF]

Does anyone use the quantity of "mole" anymore?

Man, I am getting old!

[Southern Raider]

Originally posted by BUFF:
<STRONG>Does anyone use the quantity of "mole" anymore?</STRONG>

Yes, but this is more for chemistry. 6.023E23(?) molecules.

[EMDII]

Originally posted by Southern Raider:
<STRONG>Yes, but this is more for chemistry. 6.023E23(?) molecules.</STRONG>

Or would that be Avogadro's Number!

Man this is too fun!

[Wadman]

You guys are killing me.