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Round Terms and Definitions

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/25/2012 at 15:49
Skylar McMahon View Drop Down
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As the forum grows, there is a lot of threads with different rounds and some of the terms are not explained in detail.
 
Here is a list of terms and how they are explained.
 
Ballistic Coefficient: Is the number that represents a bullets ability to slip through the air and retain both velocity and energy. The hight the number, the more slippery the bullet, or the less it will slow down in flight.
A bullets' BCE is determined by dividing the sectional density (mas) by a form factor "I" The form factor "I" represents a bullet's ability to overcome drag resistance as air passes over the tip, nose, ogive, shoulder, body, and tail.
 
Base: The lower portion if a bullellt body. (Be aware that some individuals will also use the word base when base when referrring to the extreme end of a bullet's tail.)
 
Boat Tail: A bullet's tail that is contoured like the tail of a boat.  A boat tail improves a bullet's BCE, reduces drag and improves flight characteristics.
 
Body or Shaft: The continuous cylindrical shape of a bullet. A bullet's body extends the distance from shoulder to tail.
 
Bullet Caliber: The cross sectional diameter of a bullet measured in thousandths od an inch. A 308 caliber is three hundred and eight thousandths of an inch.
 
Bullet Energy: The primary compent of the destructive force or killing power a bullet contains and delivers to a target. Bullet energy is the ability of a bullet to destroy the layers of a target, severe nerve bundles and vascular systems, and tear tissue apart.
 
Bullet Expansion: The way a bullet deforms or opens up, as it impacts and penetrated a target. The rate at which a bullet expands affects how quickly a bullet delivers energy and structual damage to the target along the path of penetration.
 
Bullet Momentum: The secondary component of knock down, stopping, or killing power a bullet contains and delivers to a target.
Bullet momentum is the raw ability of a bullet to penetrate a target or knock it over.
Bullet momentum is calculated by multiplying the bullet's mass by it's velocity [Momentum = Mass X Velocity]
Bullet momentum is measured in LBS-FT/SEC.
 
Bullet Selection: The number of different bullet type(s) and bullet weight(s) available in a specific caliber.
 
Bullet Type(s): The variety in bullet selection, or different number if: Bullet Weights, Physical Structures, Styles, or Compositions in a specific caliber.
 
Bullet Velocity: The speed of a bullet. This is the primary component of bullet trajectory or how much a bullet will have to arch in order to reach the target.
 
Bullet Weight: The weight if the bullt measured in grains.
 (7000 grains = 1 pound)
 
Bullet: The slug or metallic projectile that leaves the weapon barrel.
 
Cartrige Load: A specific cartridge built with a specific: bullet, bullet weight, measure of powder, or a specific type powder. (A known simply as a specific load)
 
Cartridge Name: The name of the cartridge that identifies the caliber and case characteristics.
 
Cartridge: The combination of a bullet, case or shell, powder and primer. Also known as a round.
It is inaccurate to call a cartridge a bullet, simply because a bullet is a component of a cartridge.
 
Core Divider: A sectional separator, dividing wall, cross member, partition, or cup that separates the lower portion of a bullet's body from the upper section or nose.
 
Core: The internal (metallic) structure of a bullet.
 
Drag: Resistence to motion along the course of travel. Drag is typically an inverse function of velocity.(the faster something moves the more drag slows it down)
 
Efficiency(powder): A subjective measure showing bullet enery divided by powder load. This equation considers the mass and velocity if a load and divides it by tge amount of powder used to produce that level of energy. This equation is most useful when comparing loads with equal bullet wieghts.
 
Factory Load Ammunition (FL): A term used to descride ammunition that is available from a major ammunition manufacture.
 
Felt Recoil: What the shooter feels as the weapon kicks back when fired.
 
Hand Load Ammunition (HL): A term used ti describe a process of using published Reloading Data to assemble ammunition by hand.
 
Jacket: The metallic cover, or exterior skin of a bullet.
 
Load Density: The percentage of the case volume occupied by the gun powder.
 
Muzzel Energy: A bullet's energy as it leaves the barrel or muzzel of the weapon.
 
Muzzel Velocity: A bullet's speed as it leaves the barrel or muzzel of the weapon. Bullet velocity is measured in Feet per Second. ( FT/S )
 
Ogive: The form, contour or line of a bullet where it transitions from the tip of a bullet to its shoulder. (An ogive is the shape of a pointed arch or vaulted rib.)
 
Powder Load: The volume of gunpowder contained in a specific cartridge load.
There are manu different types of gunpowder. Each has a unique burn rate. Two different cartridge may have the same bullet wieght and volume of powder, but none the less produce different velocities due to different powder types.
 
Powder: The propellent that when ignited by the primer, converts into a gas pushing the bullet out the weapon's barrel. The mass of gun powder is measured in grains. (7,000 grains = 1 pound)
 
 
Professional Hunter or Dangerous Game (PH or DG): This ammunition is purpose built to harvest Dangerous Game. Norma calls these loads Professional Hunter as they are purpose for guides and professional hunters when hunting Dangerous Game in Africa. These cartidges are correctly understood as dangerous game cartridges.
 
Sectional Density: A bullet's mass divided by its cross sectional area. (caliber cross sectional area)
 
Shoulder: Where the curve(ogive) of a bullet's nose meets the bullet's boddy.
 
Tail: The bottom end of a bullet or extreme nose meets the bullet body.
 
Terminal Ballistics: The event, behaviors and results of a bullet striking the target.
 
Tip, Nose, Meplat: The first point of a stabilized bullet to impact a target when fired.
(Meplat is a term used to


Edited by Skylar McMahon - October/09/2015 at 09:46
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/25/2012 at 17:00
3_tens View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/26/2012 at 19:48
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Meplat is the nose of all bullets.
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/05/2012 at 11:41
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Originally posted by 3_tens 3_tens wrote:

Smile

+1
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/07/2015 at 10:49
Stevey Ducks View Drop Down
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The "form factor" business allows me to make hits way out there (varmints & paper targets) with my tiny speedy 6mm's instead of being painfully pounded by big .30 calibers.

Form Factor = Sectional Density/Ballistic Coefficient

"float like a butterfly - sting like a bee"

Now we have the 6.5-.300 Wby.

www.bergerbullets.com/form-factors-a-useful-analysis-tool/



Edited by Stevey Ducks - October/07/2015 at 11:32
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/08/2015 at 20:42
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Here is another term - The Taylor Knock Out Index or something like that

TKO = (weight of bullet in grains * impact velocity * bore diameter) / 7000

This puts a number on comparing a .45/70 to a .30-06. Sort of like momentum - deep continual directed penetration.

Kinetic energy = 1/2 M V * V; this value is what is shown in various ballistic tables and Mr. Taylor thoughts were that is puts a un-realistic premium on velocity as it is squared (multiplied by itself). The mass of the bullet is in a funny unit called "slugs" being the weight of the bullet corrected for gravity. 

The kinetic energy for a .30-06 shooting a 180 gr. at 100 yards would be about 2400 foot pounds.

The kinetic energy for a modern .45/70 shooting a 400 grain bullet at 100 yards would be about the same, 2400 foot pounds.

The TKO for the .30-06 @ 100 would be (180 * 2450 * .308)/7000 or 19

The TKO for the .45/70 @ 100 would be (400 * 1640 * .458)/7000 or 43; This assumes a .458 bore diameter for the real old .45/70 which may be different.

Apparently, Mr. Taylor was this old guy that shot elephants or like game.

Big guns are fun but it feels good when you stop shooting them. 



Edited by Stevey Ducks - October/09/2015 at 15:21
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/08/2015 at 21:38
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(Big guns are fun but it feels good when you stop shooting them. )

HA HA!   I like that.  Wink
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/09/2015 at 09:45
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Originally posted by Skylar McMahon Skylar McMahon wrote:

As the forum grows, there is a lot of threads with different rounds and some of the terms are not explained in detail.
 
Here is a list of terms and how they are explain.

Bullet Energy: The primary compent of the destructive force or killing power a bullet contains and delivers to a target. Bullet energy is the ability of a bullet to destroy the layers of a target, severe nerve bundles and vascular systems, and tear tissue apart.

Bullet Momentum: The secondary component of knock down, stopping, or killing power a bullet contains and delivers to a target.
Bullet momentum is the raw ability of a bullet to penetrate a target or knock it over.
Bullet momentum is calculated by multiplying the bullet's mass by it's velocity [Momentum = Mass X Velocity]
Bullet momentum is measured in LBS-FT/SEC.



Some (like me) would disagree with the use of "primary" and "secondary" with these two terms.  A poorly constructed bullet, for example, may have tons of theoretical energy, but very little destructive force or killing power.  As Skylar and I have discussed on multiple occasions, too many hunters disregard the effect of the intended target on the projectile.  That's why no one uses a ballistic tip varmint bullet on an elk.  Energy is measured by F = M * A (Mass * Acceleration), where acceleration is assumed to mean that at the impact velocity, acceleration goes from V to 0 (zero), and therefore all of the energy is transferred to the target.  The only time this happens is when a properly constructed bullet penetrates the target, has sufficient expansion, and does not pass through the target, thus all of the energy is transferred to the target.  With an arrow or a FMJ bullet that passes through the animal without fragmenting or expanding, it has retained some velocity and therefore all of the energy was not transferred.  Similarly, a varmint bullet that fragments upon - or soon after - impact, transfers velocity to the various fragments.  Some energy is transferred in either scenario, but the fallacy of using simple energy to gauge effective killing power or destruction is a trap that too many novice hunters fall into.

Just as troubling are those archers that think energy is king and justify using their light arrows going super fast.  The idea is just the opposite of firearms ballistics - in archery, you want the arrow to maintain as much velocity as possible THROUGH the target, allowing the blades to cut as much flesh (hopefully vital organ flesh) as possible.  The light, fast arrows transfer all of the energy, with less than a pass-through, but with inadequate penetration provided by MOMENTUM, lethality is vastly reduced.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/09/2015 at 10:03
tahqua View Drop Down
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Sorry but F=ma is force and not to be confused with energy, in our case kinetic

KE=1/2mv2

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/09/2015 at 10:42
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Correct, sir.  My apologies.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/09/2015 at 12:33
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No apologies needed Dec, afterall everything above stems from Newton's Second Law, F=ma.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/09/2015 at 12:46
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I'm not homophobic, but I prefer not to use the word "shaft" in conversations with all dudes.
Or mostly dudes.
Or even one other dude.
But I do see a need for common vocabulary.


Carry on.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/09/2015 at 12:54
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Stems, shafts..........bending moments....oh my
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/10/2015 at 07:25
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