Compare Cartridge A to Cartridge B (Energy)

[56hawk]

Just wondering how we should compare the energy of two different cartridges. Seems like no matter what rounds you are talking about someone always has to bring up Buffalo Bore or similar ammo to prove theirs is more powerful. This applies to any two rounds, but for example lets look at 45 Colt vs 44 Magnum.

Do you compare:

Original factory specs?
45 Colt 255 grain bullet at 860 fps for 410 ft-lbs
44 Magnum 240 grain bullet at 1470 fps for 1120 ft-lbs

Modern large manufacturer (Federal)?
45 Colt 225 grain bullet at 860 fps for 369 ft-lbs
44 Magnum 300 grain bullet at 1160 fps for 896 ft-lbs

Modern small manufacturer (Buffalo Bore)?
45 Colt 255 grain bullet at 1000 fps for 566 ft-lbs
44 Magnum 270 grain bullet 1450 fps for 1260 ft-lbs

+P vs non +p (Corbon)?
45 Colt 300 grain bullet at 1300 fps for 1126 ft-lbs
44 Magnum 260 grain bullet at 1450 fps for 1214 ft-lbs

+p vs +p+ (Buffalo Bore)?
45 Colt 325 grain bullet at 1325 fps for 1267 ft-lbs
44 Magnum 340 grain bullet at 1478 fps for 1649 ft-lbs

Reloading Data (Lyman)?
45 Colt 250 grain bullet at 969 fps for 521 ft-lbs
44 Magnum 240 grain bullet at 1292 fps for 889 ft-lbs

 

[wgaynor]

One thing to keep in mind is that despite what's written on the box, you won't get the exact results.

Too many variations come into play, including barrel length and distance of measured velocity.

Regardless, I never compare two cartridges. Each one is a tool that is meant to be used in it's own ideal way.

 

[suemarkp]

Why are you trying to compare them (to what end)? Energy isn't really the most important factor.

Velocity matters for trajectory, and has somewhat of an effect on terminal ballistics in major jumps (think in 500 fps differences here -- e.g. 2000 fps is better than 1500 fps is better than 1000 fps).

Weight matters, but it has to be taken in consideration with frontal area. A 70gr 22 will penetrate better than a 150gr 45. So find the equivalent weight (e.g. sectional density) for the calibers compared and then compare other factors to those equivalent weights. If you want more penetration, make sure your cartridge comes in the heavier bullet weights. If you want faster bullets, look to see if lighter bullets are available.

Expansion can matter for terminal ballistics, and is driven by velocity and weight. Expansion also reduces penetration. This one you pretty much need to study actual results because so much is driven by bullet design. But it is much easier to get a 1400fps bullet to expand than an 800 fps bullet to expand. However, at very long range, the velocity may have dropped so much that you'll get no expansion (so larger caliber is more effective).

Shape. Bullet shape can affect external and terminal ballistics. This matters more in what the cartridge was designed for. Historically revolver cartridges will be available in wadcutter and semi wadcutter designs. These are more effective than round nose terminally, but are less aerodynamic than round nose and spitzers. A cartridge designed for semi-autos will be constrained to rounded or truncated cone designs. You can handload and change bullet types, but there can be annoying issues to deal with if you're trying to use a given cartridge in a way it was not designed (e.g. trying to run heavy bullets in a 45 ACP revolver is problematic because heavier ones are generally .452 instead of .451 and the longer bullet can make the case bulge too much and not chamber easily).

 

[akodo]

I don't get what you are driving at?

Are you saying that people should cite something other than Buffalo Bore or other 'boutique' ammo makers when comparing energy levels? In general I'd agree with this, someone citing a 357 mag vs 30-30 comparison and using Buffalo Bore for the 357 data and Remington Express for the 30-30 is failing to compare apples to apples. However if arguing about whether it is advisable to get a 454 Casull vs a 45 LC in a modern strong frame revovler, then citing standard 454 Casull vs 45 LC from Buffalo Bore is reasonable.

OR are you trying to cite how the power of ammo has decreased in factory loads since it's inception.

Take the 357 magnum, it used to be quite common to be loaded hotter than most mainstream ammo makers do today. But there are reasons for that. Partly it is because the average bullet weight has gone down and it's easier to have higher energy levels with a heavier projectile, part of it is that 357 magnums generally aren't exclusively N-frame sized revolvers anymore so the kick of the original rounds is magnified in midsized guns, partly it is just recoil level overall, partly it is because people want less muzzle flash on self defense loads. I think these are all legitimate reasons.

ALSO ammo makers start to decrease the power of rounds as time goes by. Part of the reason is the fear that there are more and more old and possibly in poor shape guns out there in any given caliber so they want to play it a bit more safe. Part of this is also to make whatever new cartridge that just got invented (or in many cases re-invented) seem more superior than it really is.

 

[481]

Why are you trying to compare them (to what end)? Energy isn't really the most important factor.

I agree completely. However, there is a portion of the shooting public that buys into (and even prefers) the comfort offered by the oversimplification that "KE is everything".

Velocity matters for trajectory, and has somewhat of an effect on terminal ballistics in major jumps (think in 500 fps differences here -- e.g. 2000 fps is better than 1500 fps is better than 1000 fps).

Weight matters, but it has to be taken in consideration with frontal area. A 70gr 22 will penetrate better than a 150gr 45. So find the equivalent weight (e.g. sectional density) for the calibers compared and then compare other factors to those equivalent weights. If you want more penetration, make sure your cartridge comes in the heavier bullet weights. If you want faster bullets, look to see if lighter bullets are available.

Expansion can matter for terminal ballistics, and is driven by velocity and weight. Expansion also reduces penetration. This one you pretty much need to study actual results because so much is driven by bullet design. But it is much easier to get a 1400fps bullet to expand than an 800 fps bullet to expand. However, at very long range, the velocity may have dropped so much that you'll get no expansion (so larger caliber is more effective).

Shape. Bullet shape can affect external and terminal ballistics. This matters more in what the cartridge was designed for. Historically revolver cartridges will be available in wadcutter and semi wadcutter designs. These are more effective than round nose terminally, but are less aerodynamic than round nose and spitzers. A cartridge designed for semi-autos will be constrained to rounded or truncated cone designs. You can handload and change bullet types, but there can be annoying issues to deal with if you're trying to use a given cartridge in a way it was not designed (e.g. trying to run heavy bullets in a 45 ACP revolver is problematic because heavier ones are generally .452 instead of .451 and the longer bullet can make the case bulge too much and not chamber easily).

The numerous variables that you address above are probably why there is such a strong preference for the oversimplification of the "KE is everything" perspective- it is a very complex issue.

 

[jmr40]

Energy does not kill game, or stop bad guys. Penetration, placement and expansion do. But.... energy can be a fairly accurate way to predict how much penetration and expansion you get with similar rounds. It isn't an accurate way to predict what will happen when you compare a 223 to a 44 mag. The 44 gets its penetraton from its mass and doesn't really need much expansion because it is already pretty large.

But if you are comparing various 270 (or other small diameter, high velcocity loads) or various 44 ( or other large diameter slower speed) loads it can be a fairly accurate way to predict which will be better.

You also have to consider bullet construction. Some newer bullet designs get much better penetration and exansion with far less energy than you used to need. Some small bullets that traditionally would over expand and give poor penetration will now hold together and give penetration that exceeds that from older desgns that were heavier.

Energy numbers are not useless, but you do have to consider other factors along with it. Also it is easy to get into a debate over 2 rounds within 100 ft lbs of each other. Anything that close is a tie in my opinion. No person or animal you ever shoot will ever know the difference between a load that develops 700 ft lbs and another that generates 600 ft lbs as long as everything else is comparable.

 

[beatledog7]

Regardless of velocity, energy, slug weight, penetration, expansion or whatever property you want to cite, no bullet can do its job if it misses the target.

Shooting mega-loads one can't control makes no sense at all.

 

[481]

But.... energy can be a fairly accurate way to predict how much penetration and expansion you get with similar rounds.

How so?

Of the two bullet penetration models that I am presently aware of (there's one in "Bullet Penetration" by D. MacPherson and another in "Quantitative Ammunition Selection" by C. Schwartz), both are based upon Newton's second law of motion, F = ma, (all of Newton's laws of motion have to do with momentum, not energy) and both works state that KE is not the way to analyze the problem.

Can you provide an example of such a way that energy can be used to predict expansion and penetration?

 

[tomrkba]

I determine the purpose first. I compare bullet type, construction, materials, caliber and velocity and try to match it to the purpose and the firearms I have. I won't shoot a +P 44 Magnum cartridge from Buffalo Bore out of a Ruger Alaskan, but I would out of a Ruger Super Redhawk with 7.5" barrel. I check for recommendations from users of the cartridge for the purpose. Finally, I try to find some ballistic test data that show penetration and expansion. I try to match the penetration to the target; a human needs a bullet that penetrates 16-18 inches while a bear needs much more.

 

[Grey Morel]

The only thing energy figures are any good for is making a rough and ready assessment of the cartridges capabilities.

I.E. - Bullet diameter is about X size, and strikes with about Y force.

Splitting hairs about cartridges with a few percentage points more energy gains you absolutely nothing, because the end results are the same in reality.