# What % of force propells the lead?



## logan85 (May 7, 2006)

Today I was thinking about bullets and more specifically the direction of the force of the powder charge.

I have not taken any sort of physics class, so just a wild guess, I imagine that if a spherical ball of powder were to be ignited with nothing surrounding the powder, than theoretically the force from the blast would radiate equally in every direction away from the powder charge. I doubt a cylindrical chunk of powder (as what is found in a bullet) would have the exact same effect, however it is known that there is considerable pressure applied to the sides of casing (case expands) and plenty of force directed backwards (recoil).

What my question is, roughly what percentage of the force of the powder charge actually propels the bullet? Is the percentage of energy being directed to the bullet acceptable or could case designs be improved upon with "shaped charges"?

L J


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## Baldy (Jun 21, 2006)

I would think that all the ammo manufactures engineers have all that pretty well figured out. That's why most designs have stayed the same. I would think anyway.

Best Baldy..


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## Revolver (Aug 26, 2006)

The location of the powder and the compression of the powder both affect accuracy. Different powder locations will give different velocities. How a charge is compressed will affect its packing scheme and thus consistency from cartridge to cartridge.

The ideal charge is one that fills the cartridge more fully. The spherical charge will still shift throughout the cartridge and the "packing scheme" will not be locked in by compression. You have to remember that the pressure is applied to the chambers first and foremost. The brass is forced against the chamber and is incapable of containing the pressure itself.

So yes, "shaped charges" do exist and can help greatly to form consistent performance(standard deviation). The don't exist in the form of spheres but in consistently compressed cartridges.


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## Revolver (Aug 26, 2006)

Baldy said:


> I would think that all the ammo manufactures engineers have all that pretty well figured out. That's why most designs have stayed the same. I would think anyway.
> 
> Best Baldy..


Actually it was Alliant that studied the affect of charge compression interestingly enough.


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## OMSBH44 (Jul 7, 2006)

100%


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## logan85 (May 7, 2006)

OMSBH44 said:


> 100%


But if 100% of the energy from the powder were going down the barrel, than we would have no recoil - unless I am mis-understanding the laws of physics (which is entirely possible).

L J


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## Revolver (Aug 26, 2006)

logan85 said:


> But if 100% of the energy from the powder were going down the barrel, than we would have no recoil - unless I am mis-understanding the laws of physics (which is entirely possible).
> 
> L J


Does "For every action, there is an opposite and equal reaction" sound familiar?


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## Bob Wright (May 10, 2006)

*Pressure*

The pressure is equal inside the cartridge case in every direction, the bullet being the only yielding factor. Movement can only occur in two directions, forward, driving the bullet outward, and rearward, driving the gun rearward.

As to the percentage of energy, that is best described as the ratio of gun weight to bullet weight. If the gun were not restrained, and weighed the same amount as the bullet, same velocity, neglecting friction and/or air resistance.

Bob Wright


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