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Old December 26, 2012, 01:40 AM   #6
arcticap
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Join Date: March 15, 2005
Location: Central Connecticut
Posts: 2,973
Quote:
Originally Posted by warbirdlover
The bullets used with the sabots are .45 cal and not .50 cal so you lose knockdown power(?)
IMO the answer to the question above is false.
One way to measure knockdown power or lethal energy is to examine a bullet's sectional density verses another.

Sectional density has been described in the following ways:

Quote:
SD is important because it has a significant effect on penetration. Other things being equal (like impact velocity, bullet design and material, etc.) the higher the SD number, the better the bullet's penetration. In other words, a skinny bullet of a given weight tends to penetrate better than a fat bullet of the same weight, because it concentrates the same force on a smaller area of the target. For example, if other factors are equal, a 150 grain .270 bullet will penetrate better than a 150 grain .35 caliber bullet. Penetration is important because the bullet must get well inside an animal to disrupt the functioning of its vital organs. A bullet that fails to penetrate the fur, skin, muscle and bone necessary to reach the vital organs is very unlikely to bring an animal down.

http://www.chuckhawks.com/sd.htm
Quote:
Sectional density is the ratio of an object's mass to its cross-sectional area. It conveys how well an object's mass is distributed (by its shape) to overcome resistance. For illustration, a needle can penetrate a target medium with less force than a coin of the same mass...
...Sectional density is often used in gun ballistics where sectional density is the ratio of a projectile weight, to its diameter.
...Within terminal ballistics, the sectional density of a projectile is one of the determining factors for projectile penetration.
...Only if all other factors are equal, the projectile with the greatest amount of sectional density will penetrate the deepest.

http://en.wikipedia.org/wiki/Sectional_density
What this means is that a .45 caliber 245 grain bullet will have a greater sectional density than a .50 caliber 245 grain bullet and will penetrate deeper. Therefore, it's possible that depending on the bullet construction and expansion, that the .45 caliber bullet will have greater knockdown power on a large game animal than the .50 caliber Powerbelt.
Think about which bullet will deliver more lethal energy to an animal with a tough hide and large body mass.
The .45 will create a deeper wound channel into the vitals of the animal. And if the .45 has a controlled expansion factor built into its construction, then it may not blow up or fragment as easily as a nearly pure lead Powerbelt.
Fragmentation of Powerbelts has been known to occur when fired at higher velocities and closer ranges. And the deer can end up not being recovered.
I'm not picking on the Powerbelts, but every bullet has its own advantages, disadvantages and sectional density. Larger caliber bullets are not always better because they can slow down quickly after hitting the animal if they expand too fast or aren't heavy enough for their diameter.
And similarly, it's possible that a .44 caliber bullet could be better than a .45 or .50 PB of the same weight. I don't know all about the sectional density ratings and bullet construction and the other factors involved in delivering knockdown power, or even how to define knockdown power. But there are good bullets and better bullets, and depending on the shot taken some bullets are better than others. And sectional density and how well a bullet penetrates is part of it.

Last edited by arcticap; December 26, 2012 at 01:49 AM.
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