Cartridge Efficiency

[jtmoose]

I was looking at some tables and noticed that most highly effective/popular cartridges produce approximately 500# of energy at their supersonic threshold distance. Is this a good indicator of efficiency of the cartridge? If it has a longer SS threshold than it can produce 500# of energy is it too "weak" for general purposes. Similarly, if it produces 500# at greater distances than it is supersonic is it too overpowered for general purposes?


308 = .97
30-06 = .99
270 = .83
7 mag = .92
300 mag = 1.13

These numbers indicate, a 270 and 7mag are ballistically superior past effective 500# distance, 300 win mag is a little more powerful than its ballistic stability, and 308/30-06 are about a perfect balance.

 

[Rich Coyle]

How did you generate your information?

 

[jtmoose]

I made a couple tables from different factory loads using jbm calculator.

 

[Mikecr]

IMO your thinking is flawed from the git go with the bias: "most highly effective/popular cartridges".
True science is not popular, and highly effective is completely subjective.

For instance, in my mind 'highly effective' is tied to accuracy per distance rather than knock down power. I see accuracy as king of all powers. But that's me.
Then there is the departure from ACTUAL cartridge efficiency, which amounts to a lot more than heavy bullets sent down range. Some of the most efficient cartridges as far as % of powder burnt (inside the barrel) are underbores like the 6PPC and 30br, which use light for cal bullets. And as far as distant accuracy, I would suggest a typical 6Dasher would leave your choices so far -way way behind.
We just do too many things with guns to conjure rules of thumb.

Now I'm aware the most folks see guns as destructive devices. They reach for power within this theme. Growing up I've seen deer hit with everything, and they usually die all right. But they usually run a ways beforehand (conscious and nothing to lose). You could slap a deer in the side with a 50 **** BMG at point blank range, and it'll run somehow with broken shoulders and vitals flopping (a little ways)..
4-5yrs ago while groundhog hunting with a 223 and 50gr FB BR bullets, I showed a farmer the power of accuracy by dropping a deer with a brain shot at 590yds (his request, not mine). That deer folded straight down, it never knew it died or that anything was wrong at all. Just lights out. The doe next to her, looked up and then calmly went back to grazing.
I didn't need knock down power. I needed 1/4moa of accuracy from 27gr of H322.
Seems pretty efficient to me

 

[FEENIX]

I made a couple tables from different factory loads using jbm calculator.

Please do share ...

 

[Bart B]

Cartridge efficiency to me is how many fps per grain of a given powder for a given bullet weight and caliber in the same barrel length. Barrels for a given caliber must have identical rifling, bore and groove dimensions and peak pressure must be at SAAMI spec for the cartridge.

For example, think about a .30-06 with 100 and 200 grain bullets fired with IMR4198 and Retumbo.

 

[ntg]

I was thinking along the lines of Bart B. It amazing me when you compare all the extra powder you have to add to get a little more FPS in some comparisons.

 

[Bart B]

Cartridge efficiency to me is how many fps per grain of a given powder for a given bullet weight and caliber in the same barrel length. Barrels for a given caliber must have identical rifling, bore and groove dimensions and peak pressure must be at SAAMI spec for the cartridge.

For example, think about a .30-06 with 100 and 200 grain bullets fired with IMR4198 and Retumbo. You could not get enough of some powders in some cartridge and bullet combinations to reach SAAMI pressure specs.

 

[jtmoose]

As i look at the numbers closer, this ratio might be more of an indicator of energy efficient bullet weight being 165-180 than cartridge efficiency. The magnums shooting those weight bullets are closer to 1 also.