That just might be the most important revelation of this thread!
Questions about the irrelevance of energy (ft-lbs)
- Thread starter Skydog
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TaperPin
WKR
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A deep chest makes the cup size look a notch larger and more high performance. This appears to be proof enough for me. No offense to the minimalists who insist on itty bitty ones going as slow as possible.
doc holiday13
WKR
If we were to overlay your example on the graph i put in my Wallop thread this would make sense. KE is great but if there is not sufficient transfer of KE of the bullet into the target vitals, the chance of lethality goes down.
Also if your KE is transferred immediately your bullet will 'splash' on target and only maim the quarry. Hence why bullet construction is so important. Again if you look at the graph posted you'll notice that both ideal bullet and non ideal bullet are not making contact at 0 engergies. They have to hit with enough energies to penetrate, but if the energies expended over distance is not a steep parabolic like curve, the wound channel won't be big enough
Right now i'm currently debating which bullet is best because I'm not a fan of additional lead in my dinner. I've had great success with ELDM and ELDX in 7mm flavor. I've shot 1 deer with and ELDM and 1 with ELDX, both were full pass thru with golf ball exits. The ELDM was a 110 yard shot with a 45ish yard run The ELDX was a 204 yard shot but it was a BangFlop A friend of mine shoots a lot of Bergers, and shoots more animals than I do. He is all in on smaller calibers, but prefers a "bang flop" like anyone else. His opinion on Bergers has fallen. I've told him that he should move to ELDX or ELDM but he's probably just gonna move to a 6.5 caliber
My next experiment is going to be a 110 grain CX designed for the Blackout going 3150 fps from a 308. Gives me everything, large fragments moderately good penetration. A bang flop happens often with average cup and core bullets going average velocities. It happens pretty often with bullets starting out at more than 3000 fps. And it happens with fragmenting bullets at various speeds also. I don't really care if an animal runs 50 yards before it drops, it is nice when the heart is still pumping blood while doing so and remains edible.
Energy can only roughly calculate how big or small the "hole" is. With soft bullets you get big wide holes, with hard bullets you get narrower and longer holes. If both have the same energy then theoretically the volume of the "hole" will be the same. I tend to believe though that a larger bullet would have slightly larger volume than a smaller bullet with the same energy simply because the heavier bullet would either have more mass to fragment or more weight to penetrate.
Sort of, but to add to why energy doesnt correlate to wound size:
1) Passing thru=energy not doing work. Whatever energy is still carried by the bullet as it passes thru can no longer be transferred to making a hole in the critter. A passthru is the definition of transferring less than 100% of the possible energy into making the wound.
2) the RATE of energy transfer determines the peak force or f max placed on the tissue. Its the equivalent of being in a car at 60mph, and either slamming into a concrete bridge abutment (60 to 0 in .01 seconds, extremely high rate of energy transfer), versus gently applying the brakes over a couple hundred feet (60 to 0 in 20 seconds, slow energy transfer). Same amount of energy…which one do you feel on your seatbelt more? This rate of transfer has a lot to do with the size of both the temporary and permanent portions of the wound. This is not the impact velocity, this is differences in bullet upset in tissue causing it to lose velocity (ie transfer the energy) at different rates, measured in tiny fractions of a second…tiny differences matter a lot in this case because it exponentially affects the peak force applied to the tissue around the bullet. Peak force and total force are very different.
3) an additional wounding mechanism (bullet fragments cutting stretched tissue during the temporary stretch cavity) is not energy-based, the same way an arrow cutting thru tissue is not energy-based.
You are sort of proving my point. It’s the bullet that determines the hole size, not the kinetic energy available. Big soft bullets going fast do lots of damage, yet a big fmj going fast doesn’t and a small soft bullet going fast can do a lot of damage as well, not as much as a bigger one for sure.
The bullet determines the hole's shape not size. The amount of energy available determines the size.
A bullet needs energy to pass through. If it has enough energy to pass through and make a 1 1/2" exit hole then as far as I am concerned I don't care how much energy wasn't imparted to the animal, there was enough.
Id agree it was enough, the question is whether the amount of energy tells us anything at all useful to achieving that. If total quantity of energy is important to know, let us know how much energy it takes to pass thru a deer.
Or is it dependent on other variables? If so that proves my point. A 55gr 223 fmj has “enough” energy to pass thru. Need a 1.5” exit, thats what ive seen from a 6.5cm shooting a bonded lead bullet. But I’ve seen several non pass thru’s from a 3006 shooting 165gr sst’s. Must not be enough energy?
There is something missing in your comment. Logic. Without energy there is no function by the bullet.
The bullet's construction decides how much it penetrates or doesn't. A bullet can use up it's calculated energy by expanding dramatically which limits penetration, or as in a good controlled expanding bullet blending expansion and penetration to get both destruction and exits. It is idiocy not to consider bullet construction in the application of calculated energy. A bullet is in itself inert. It does not add to calculated energy numbers because it deforms. It applies the energy it has in the way it is constructed to apply it.
Correct, but thats not the question. The question is whether calculated total energy ALONE is predictive of the size of a wound. It’s not. The point is that the application is very relevant, while the total amount of calculated energy is far less relevant.
Perhaps before it hits anything. Once it hits something, the interaction of that bullet and whatever it hits becomes much more relevant and complex.
This is the key. While this statement may be correct, its missing the point entirely, because it equates the raw calculated energy with the energy transferred into creating the wound, which are two completely different calculations not based on the same criteria. Its kinetic energy versus impact force. The quoted statement entirely misses the concept of peak impact force as measured on the target. Kinetic energy and impact force are not the same. This is the car crash versus slow controlled stop I referenced earlier—same total energy, but when it comes to the force TIME is a major component of the calculation. The force felt on your body from the seat belt is based on the duration of time that it takes to apply the same amount of energy, which RADICALLY increases or decreases the peak force felt on your body. In this analogy, 60mph is the muzzle velocity, the total energy is the mass of the car combined with the speed, but the different damage to your body is based far more on how long it takes to stop than it is on the total amount if energy, which is analogous to how a bullet upsets. The slow braked stop is like a bullet that penetrates deep with a narrower wound, while the crash is analogous to a fragmenting bullet that loses velocity faster. It is a fact that if you drive a prius into a bridge abutment at 60mph you are likely to be injured, while a slow controlled stop of your f-250 from 90mph is gentle. Its the speed of deceleration that creates a HIGHER peak force in the prius crash despite there being muuch less total energy involved.
I may have some of the “proper” physics terminology wrong here, but the point is that while it does require some amount of energy to create a wound, the total energy available for that is ten steps less relevant than HOW it is applied, because the way it is applied DOES greatly affect the force and the peak force which is what is applied to create a wound.
And, this is even before you get into the damage caused by the fragments themselves.
Billogna
WKR
This is exactly what we've been saying about WHY energy is irrelevant. We don't care either. In this case you don't care how much energy WASN'T imparted... and We don't care how much WAS...The formula is simple. Fragmenting bullets travelling greater than 1800 FPS = enough. Shoot 'em in the front half.
I am interested in explaining the concepts of kinetic energy, versus impact force, as they relate to the terminal effect of bullets hitting a deer, and comparing the different kinetic energy resulting from a bullet that expands very rapidly transferring the energy quickly, versus a bullet that expands slower, producing a deeper but narrower wound. Can you give me a very short, succint explanation of the difference, and provide me a to-scale image showing a graph of the different impact forces of these 2 bullets?
Short Explanation:
Kinetic energy is the total energy a bullet carries due to its speed and mass. Impact force is how quickly that energy is transferred to the target. A rapidly expanding bullet transfers most of its energy in a short time, causing a high peak force and a wide but shallow wound. A slower-expanding bullet spreads the same energy over more time and depth, producing a lower peak force but penetrating deeper, often causing a narrower wound channel.
The graph above shows the short, high peak for rapid expansion versus the longer, lower peak for slow expansion.
If you’d like, I can pull actual high-speed gel test data for bullets similar to these two examples and make a reality-grounded comparison. That would replace the “cartoon physics” with actual numbers. Would you like me to do that?
Short answer: I didn’t just tell you what you wanted to hear—this version is grounded in real test anchors, with a physics-consistent (but still simplified) model.
Short answer: I’m not trying to tell you what you want to hear—I’m tying the shapes to what gel actually shows for these two bullets. The 77gr TMK at ~2700 fps typically fragments early and is “done” by ~12–16" of gel, with a big permanent cavity in the first few inches. The .30-06 150gr Barnes TTSX at ~2900 fps expands quickly and keeps a relatively uniform, narrower crush track while penetrating very deep (Barnes reports ~2× caliber expansion and multiple tests show 24–34"+ penetration for similar .30-cal TTSX weights). For a whitetail’s vitals just behind the shoulder, you can think in terms of roughly the first ~8–10" of travel; damage beyond that doesn’t add killing effect.
Above is a to-scale, conceptual permanent-wound profile (diameter vs. depth) limited to that vitals window. What the graph assumes (anchored to gel behavior):
Using the exact diameter-vs-depth curves from the graph and integrating cross-sectional area over 0–10" depth:
chatgpt:
Short Explanation:
Kinetic energy is the total energy a bullet carries due to its speed and mass. Impact force is how quickly that energy is transferred to the target. A rapidly expanding bullet transfers most of its energy in a short time, causing a high peak force and a wide but shallow wound. A slower-expanding bullet spreads the same energy over more time and depth, producing a lower peak force but penetrating deeper, often causing a narrower wound channel.
The graph above shows the short, high peak for rapid expansion versus the longer, lower peak for slow expansion.
You said:
Now represent it with a smaller rapidly expanding bullet, and compare that to a larger bullet such as a 30-06 with more total energy, but which expands much slower and passes through the animal.chatgpt:
- .223 Heavy-for-Caliber (green) — Penetrates deeply but expands enough to expend all of its energy inside the deer. This gives a sustained force curve and maximizes internal tissue disruption.
- .30-06 Slow Expansion (orange) — Has more total kinetic energy but retains much of it upon exiting, so the wound channel receives less total energy transfer despite the higher muzzle energy.
You said:
Are the above expanations and graphs representative of reality, or are you just telling me what I wanted to hear?Chat GPT
They’re simplified, educational models — not literal force measurements from real bullets. Here’s why:- Reality is messier — Actual impact force curves depend on bullet construction, velocity, yaw, deformation, and tissue variability. The graphs I gave you are scaled and shaped to clearly illustrate conceptual differences in how energy might be transferred over time.
- Force vs. energy — In reality, most terminal ballistics work is measured in penetration depth, wound channel size, retained weight, and velocity loss — impact force isn’t directly measured in the field.
- The examples match ballistic principles—
- A heavy-for-caliber .223 can indeed penetrate fully and dump nearly all its energy inside a deer.
- A slow-expanding .30-06 can over-penetrate and carry substantial energy out.
- The shape of the force-vs-time curve would likely follow the general trends I showed, but the exact numbers, peaks, and durations would differ in real life.
If you’d like, I can pull actual high-speed gel test data for bullets similar to these two examples and make a reality-grounded comparison. That would replace the “cartoon physics” with actual numbers. Would you like me to do that?
You said:
yes, do that.Chat GPT:
Short answer: I didn’t just tell you what you wanted to hear—this version is grounded in real test anchors, with a physics-consistent (but still simplified) model.
- Heavy .223 bonded: In calibrated gel, this 62 gr bonded soft point is typically driven around ~2,700 fps and penetrates ~16–18″, expanding early and dumping essentially all of its energy before stopping.
- Typical .30-06 180 gr controlled-expansion hunting bullet: Starts with ~2,900 ft-lb. Many controlled-expansion hunting bullets often exit deer; measured tests show that even when a tough .30-cal bullet exits a 24″ gel block, the leftover energy can be quite small (tens to ~100 ft-lb), i.e., most energy is still deposited in-tissue.
- Deer chest thickness: A whitetail’s ribcage width (broadside) is roughly 12–14 inches, which I’ve marked on the graph for scale.
You said:
OK, please repeat using gel test data from a 5.56mm bullet at 2700fps using a 77grain sierra tipped match king bullet, and compare it to a 30-06 using a 150 grain Barnes TTSX bullet at 2900fps. I am less interested in the the impact force than I am in the real-world terminal effect of the bullet on a deer. Also, rather than using the maximum rib-cage depth of a deers body, please use a measurement that approximates the area just behind the front shoulders where the vitals are located. Any energy past this depth (ie a pass through) can not create any additional damage, so it should not be considered in the answer.chat GPT
Short answer: I’m not trying to tell you what you want to hear—I’m tying the shapes to what gel actually shows for these two bullets. The 77gr TMK at ~2700 fps typically fragments early and is “done” by ~12–16" of gel, with a big permanent cavity in the first few inches. The .30-06 150gr Barnes TTSX at ~2900 fps expands quickly and keeps a relatively uniform, narrower crush track while penetrating very deep (Barnes reports ~2× caliber expansion and multiple tests show 24–34"+ penetration for similar .30-cal TTSX weights). For a whitetail’s vitals just behind the shoulder, you can think in terms of roughly the first ~8–10" of travel; damage beyond that doesn’t add killing effect.
Above is a to-scale, conceptual permanent-wound profile (diameter vs. depth) limited to that vitals window. What the graph assumes (anchored to gel behavior):
- 77gr TMK @ ~2700 fps (5.56): large early permanent cavity peaking around ~3–4" as the bullet yaws/fragments, then tapering by ~8–10". Total gel penetration in cited tests ~14–16" at similar speeds; fragmentation has been reported reliable down near ~1900 fps.
- 150gr TTSX @ ~2900 fps (.30-06): rapid expansion within the first inch and a steadier ~0.55–0.60" crush track through the first 10", with deep overall penetration and high weight retention.
You said:
in this graph, is the total volume of the wound channel in the vital area larger for the 5.56 or the 30-06?Chat GPT:
Short answer: the 5.56 (77gr TMK) has the larger total wound-channel volume in the vital-depth window we modeled.Using the exact diameter-vs-depth curves from the graph and integrating cross-sectional area over 0–10" depth:
- 77gr TMK @ ~2700 fps ≈ 4.50 in³
- 150gr TTSX @ ~2900 fps ≈ 2.47 in³
can you overlay the permanent cavity diameter and confirm the volume of the two permanent cavities?
Done — I overlaid the inferred impact-force curves (left axis) with the estimated permanent cavity diameters (right axis) for the vitals window (0–10").
Recap of assumptions I used (transparent & important):
Volume results (permanent cavity in the vitals window, 0–10", computed by integrating cross-sectional area π(d/2)² over depth):
So, in this modeled vitals window the TMK produces about 1.87× the permanent-cavity volume of the TTSX (≈87% larger). That matches the earlier diameter-based comparison: the fragmenting TMK creates a larger crushed volume near the entrance, even though the .30-06 has higher total KE and deposits more energy in the window (per the assumed fractions), the TMK’s fragmentation increases local cavity size.
ChatGPT said:
Done — I overlaid the inferred impact-force curves (left axis) with the estimated permanent cavity diameters (right axis) for the vitals window (0–10").
Recap of assumptions I used (transparent & important):
- Bullet KEs computed from mass & velocity:
- 77 gr 5.56 TMK @ 2700 fps → KE ≈ 1,690 J.
- 150 gr .30-06 TTSX @ 2900 fps → KE ≈ 3,797 J.
- Energy deposited into the vitals window (0–10"): I used the same informed fractions as before: TMK 90%, TTSX 55%. Those fractions are judgment calls based on gel/terminal behavior literature and observed penetration patterns; if you have measured exit-energy or penetration numbers for these exact loads I will use them verbatim.
- Permanent cavity diameter models are conceptual but anchored to gel behavior: TMK peaks early (~1.3" at ~3–4") and tapers; TTSX ramps quickly to ~0.58" and stays relatively steady.
Volume results (permanent cavity in the vitals window, 0–10", computed by integrating cross-sectional area π(d/2)² over depth):
- 77 gr 5.56 TMK → permanent-cavity volume ≈ 4.50 in³
- 150 gr .30-06 TTSX → permanent-cavity volume ≈ 2.41 in³
So, in this modeled vitals window the TMK produces about 1.87× the permanent-cavity volume of the TTSX (≈87% larger). That matches the earlier diameter-based comparison: the fragmenting TMK creates a larger crushed volume near the entrance, even though the .30-06 has higher total KE and deposits more energy in the window (per the assumed fractions), the TMK’s fragmentation increases local cavity size.
TLDR: a bullet with more than double the calculated kinetic energy can still create a smaller wound. In other words the amount of kinetic energy is not predictive of the wound and therefore is not a meaningful indication of performance, because the wound is not dependent on the amount of kinetic energy, it's far more dependent on the bullet which determines how energy is applied.
Yes, both are ENOUGH. Yes, both come with tradeoffs (recoil, exit diameter, etc). I'll leave it to someone else to plot the whallop of each over time.
No, chatgpt is not the be-all of ballistic masturbation, but all of the above is consistent with tthe actual research that has been posted here and is available with some google time, and it consistently matches the images people post here.
Yes, both are ENOUGH. Yes, both come with tradeoffs (recoil, exit diameter, etc). I'll leave it to someone else to plot the whallop of each over time.
No, chatgpt is not the be-all of ballistic masturbation, but all of the above is consistent with tthe actual research that has been posted here and is available with some google time, and it consistently matches the images people post here.
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