Muzzle Energy Formula

Wadman · June 28, 2001, 10:07

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** · June 28, 2001, 10:29

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** · June 28, 2001, 11:09

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 · June 28, 2001, 11:44

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 · June 28, 2001, 13:29

Quote:

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

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

doubletap · June 28, 2001, 20:30

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** · June 28, 2001, 20:40

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

krf

**BUFF** · June 28, 2001, 23:59

Does anyone use the quantity of "mole" anymore?

Man, I am getting old!

Southern Raider · June 29, 2001, 05:17

Quote:

Originally posted by BUFF:
Does anyone use the quantity of "mole" anymore?

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

**EMDII** · June 29, 2001, 06:07

Quote:

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

Or would that be Avogadro's Number!

Man this is too fun!

Wadman · June 29, 2001, 07:33

You guys are killing me.

June 28, 2001, 10:07	#1
Wadman Registered FALaholic #: 1095 Join Date: Sep 2000 Location: North East Illinois Posts: 2,820	Muzzle Energy Formula 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 ] __________________ The low road is frequently a four lane highway with no speed limit. Help Save the Kitties

June 28, 2001, 10:29	#2
BUFF Old Fart Silver Contributor FALaholic #: 789 Join Date: Aug 2000 Location: Salt Lake City, Utah Posts: 7,133	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 ] __________________ BUFF

June 28, 2001, 11:09	#3
EMDII Evil Moderator Silver Contributor FALaholic #: 6 Join Date: Jul 2000 Location: Kennesaw, GA Posts: 13,971	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 ] __________________ "The Spartans do not enquire how many enemy there are. The SPartans merely enquire WHERE they are." E.M. (Ted) Dannemiller II 1*

June 28, 2001, 20:40	#7
K. Funk Real Life Metallurgist Gold Contributor FALaholic #: 38 Join Date: Jul 2000 Location: Myerstown, PA Posts: 3,938	I haven't heard the term "slug" as applies to physics for years. Hats off to you mad ballistic physicists. krf __________________ The Mason-Dixon FAL Association wants YOU!! Ask me for details. You never know what's going on inside the mind of a crazy man!! Check out username kandainv on Gunbroker; always some neat stuff!! FYB!!!!

June 28, 2001, 23:59	#8
BUFF Old Fart Silver Contributor FALaholic #: 789 Join Date: Aug 2000 Location: Salt Lake City, Utah Posts: 7,133	Does anyone use the quantity of "mole" anymore? Man, I am getting old! __________________ BUFF

June 28, 2001, 11:44	#4
Southern Raider Registered FALaholic #: 2045 Join Date: Jan 2001 Location: Reno, NV Posts: 166	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.

June 28, 2001, 20:30	#6
doubletap Registered FALaholic #: 1426 Join Date: Oct 2000 Location: Northern Taiga-land Posts: 828	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

June 29, 2001, 07:33	#11
Wadman Registered FALaholic #: 1095 Join Date: Sep 2000 Location: North East Illinois Posts: 2,820	You guys are killing me. __________________ The low road is frequently a four lane highway with no speed limit. Help Save the Kitties

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