Bullet grain help?

IM Lugger:

KE = 1/2 Mass x velocity squared

The units used matter not - except that you must use the same units for all constants and variables.

thus:

KE = 1/2 (mass,gms)x(velo,m)squared
or
KE = 1/2 (mass, lbs) x (velo, fps) squared
....

you guys are all arguing on the right side....



Back to ALEX:

a grain is 1/7000 of a pound

the more grains a bullet is the heavier it is...

penetration / shock / energy is a huge topic .... you will need to buy me many beers before I will try to explain it.. and then I will be wrong once some one else hears my reasons.

In short ( VOODOO) - well not really but you have to subscribe before you judge...

:mrgreen:

OMFG this is all funny... cheer up all...
 
I think this mite have vered of topic. It all depends on what you are shooting ( ipsc , ppc, bullseye) The rule of thum is heaver the bullet less felt recoil. For example a 9mm 124gr bullit would have less felt recoil then a 115gr. but people sayt the 115 cycle faster wich is false. Bullit weight does not make the gun cycle faster the case size does. example is in ipsc open class a9mm major gun will cycle faster then 38 super the case is shorter you can set the gun up that the slide goes not have to travil as fare to eject the case. Remember the slide of a semi-auto cycles at about
.04 -.06 sec. I do not know anybody that can out shoot ther gun. It all comes down to what you are comfortable with experament with difrent weights buy a box diffrent weights for the cal you are shooting. Just my.02
God I am long winded sorry :lol:
 
IM_Lugger said:
that's exactly my point; you have to use m/s and kg and get the figure in joules, whay do all the conversions :roll:
Click to expand...


Mass, time, and length are the base dimensions, no matter what they are.

Energy, velocity, and all the rest are derived dimensions, e.g. energy = mass times distance squared, divided by time. Velocity is distance divided by time.

energy iscalculated as 1/2 mass times velocity times velocity, no matter the units. If feet, slugs, and seconds are used, the derived unit of energy is the foot pound. If meters, kilos, and seconds are used, the derived unit of energy is the joule. If grains, yards, and seconds are used, the derived unit of energy is grain yards squared per second.

It's all still the same amount of energy. the way to calculate it is 1/2mv^2. So long as the units are consisitent, the math always works out.


Before you ask, typos aside, yes I am sure.
 
rotncore said:
It's the weight of the bullet, bigger grain is heavier, therefore harder hitting (more recoil) and more stopping power. The best way to figure which is best is to experiment, as long as your gun can handle the grain of the bullets you use.
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Not correct 100% (higher grain has lower velocity in general)

Taken from
http://www.ipsc.org/pdf/RulesHandgun.pdf
Power Factor = bullet weight (grains x avererage (fps) /1000

Still that is not 100% right for STOPPING power (that is their power factor rating)

Stopping power would be the ENERGY transferred to the target.
the calculation is E=(1/2)(m)*(v^2). (e=energy in joules, m=mass in kilograms, v=velocity in meters per second) This formula heavilty favors the velocity.

Keep in mind all energy would have to be transferred to the target. Meaning Hollow point or defensive rounds would transfer more energy as others may penetrate through the target and continue.

Many defensive bullets are actually very low grain and have high velocities.

From experience (comparing same BRAND of factory ammo).
.45ACP 230gr give noticable more recoil in all aspects than 185gr.
.40s&w 165gr give snappier recoil compared to 180gr that feels less snappy but more push.

You can make your own comparisons easiest by missing ammo in your mag. Different brands may yeild different results.

Realoading your own allows you make hotter loads. That will give you more power ;)

Also heavier grain shoots lower in general since it takes longer to get to the target.

-20-
 
I just need to ask:
How did you get a restricted P.A.L. and not understand bullets?
you would have had to go through two classes ( or challange), so how do you get to buying 1000rnds, if you dont know what it is you're looking for?
 
MOBILE 1 said:
The rule of thum is heaver the bullet less felt recoil.
Click to expand...

Not quite true. For a non-compensated gun the heaviest bullet in conjuction with the fastest powder yeilds the least perceived recoil. The opposite is true for compensated pistols (lightest bullets & slowest powder)
 
hoochie said:
I just need to ask:
How did you get a restricted P.A.L. and not understand bullets?
you would have had to go through two classes ( or challange), so how do you get to buying 1000rnds, if you dont know what it is you're looking for?
Click to expand...

Since the tests were geared towards safety, there wasn't a whole lot on Bullet grain info. Also, I'm pretty sure the people on thos forum have alot more information on it than 2 books. That's quite obvious, looking at the posts in this thread. Can you sit there and honestly tell me that this thread hasn't taught you anything?
 
this 1/2 mass formula is for transitional KE. if you take a ball with a mass of 1kg and throw it at 1m per second what do you get for KE?
 
1/2 M V^2, so, you get

1/2 * 1kg * 1m/s * 1m/s = 0.5 Kg*m^2/s^2

since 1 Kg*m/s^2 = 1 Newton,

the Kinetic energy is 1/2 Nm, and a Newton * a meter is defined as a Joule.

So the kinetic energy is 0.5 Joule.

What is "transitional KE"? In 8 years of undergraduate and graduate education in mechanical engineering, I've never heard of it. I figure it must be a "personal" term used by a given instructor to help describe the tradeoff beween kinetic and potential energy involved in conservation of energy in ballistics (what goes up, must come down).
 
Mass, time, and length are the base dimensions, no matter what they are.
Click to expand...
IM Lugger:

KE = 1/2 Mass x velocity squared

The units used matter not - except that you must use the same units for all constants and variables.
Click to expand...

OK if that’s true please tell me what I’m doing wrong, ‘cause this doesn’t make sense to me… :?

K=½ m * v^2

I’m going to use 124gr bullet at 1100fps, so

K=½ (124)* (1100^2)
K=½ 124*1210000
K=75020000 ----that’s if I multiply 1/.2 by 124 first

The number should be 333 if in ft-lb


http://en.wikipedia.org/wiki/Muzzle_energy

this is a good site on ballistics
http://www-medlib.med.utah.edu/WebPath/TUTORIAL/GUNS/GUNBLST.html
 
IM_Lugger said:
Mass, time, and length are the base dimensions, no matter what they are.
Click to expand...
IM Lugger:

KE = 1/2 Mass x velocity squared

The units used matter not - except that you must use the same units for all constants and variables.
Click to expand...

OK if that’s true please tell me what I’m doing wrong, ‘cause this doesn’t make sense to me… :?

K=½ m * v^2

I’m going to use 124gr bullet at 1100fps, so

K=½ (124)* (1100^2)
K=½ 124*1210000
K=75020000 ----that’s if I multiply 1/.2 by 124 first

The number should be 333 if in ft-lb
Click to expand...


I thought you were going to teach the rest of us...... :roll:

IM_Lugger said:
Don’t want to turn this into physics class but you’re wrong....
Click to expand...
 
So are you going to roll your eyes or explain how the formula you claim to be right works?

At least I proved that mine works.... :wink:
 
RePete said:
Bartledan:

I knew that arithmetic would come in handy some day.

Just think, that answer above cost you about $30,000. :lol: :lol: :lol:

RePete.
Click to expand...

More like $50,000. I have a $30,000 ring. I'll show it to you sometime. It's made out of the cheapest stainless steel available, and took 30 seconds to punch out in a factory.
 
IM_Lugger said:
So are you going to roll your eyes or explain how the formula you claim to be right works?

At least I proved that mine works.... :wink:
Click to expand...

You've gotten an answer (I won't bother to check your arithmetic), expressed in grain feet squared per second squared.

Now, if everyone else computed it using such silly base units, you could compare them directly.

Instead, everyone else uses the common conventions of the metric system (mks), or the imperial system (ft, slug, second), so their results can compared directly. That, ande that alone is the utility of using unit conventions. Pineapple or Anana, it's the same fruit.

Now go back, and read my first post in this thread again. Carefully, this time.
 
alexlacelle said:
hoochie said:
I just need to ask:
How did you get a restricted P.A.L. and not understand bullets?
you would have had to go through two classes ( or challange), so how do you get to buying 1000rnds, if you dont know what it is you're looking for?
Click to expand...

Since the tests were geared towards safety, there wasn't a whole lot on Bullet grain info. Also, I'm pretty sure the people on thos forum have alot more information on it than 2 books. That's quite obvious, looking at the posts in this thread. Can you sit there and honestly tell me that this thread hasn't taught you anything?
Click to expand...

very true.. they just teach the basics...
basically "more grain the heavier"
and stuff like what the different bullet heads do.
 
I read somewhere that heavier bullets penetrate deeper than lighter bullets. Second, since heavier bullets cannot be driven as fast as lighter bullets, they experience less impact stress and are therefore less likely to fracture upon impact. This is very important, as the amount of stress experienced by a bullet upon impact is the result of the speed of impact and the toughness of the target. When the target is close and extremely tough, reliable performance is always best achieved by increasing bullet weight and decreasing velocity. The importance of selecting a bullet with a broad meplat is also critical, as broad meplated bullets tend to penetrate deeper than small meplated bullets.
 
Bartledan,

I've often thought of including the bullets rotational energy into this equation, although it would really present no *meaningful* "impact" energy data. But in theory - one could sum both the "actual" KE and the rotational KE and get a true KE, correct? Or am I out to lunch on this?
 
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