Infantry Discussion Thread part 11: Gallas Razor edition.

[Manokan Republic]

The round does have more drop... the trajectory is flatter

If it has more drop it is the opposite of flatter. Drop is caused by gravity, which acts on all things identically. A slower projectile has more drop than a faster one.

You botched the comparison by using the same zero and different superelevations.

More consistent drop, but my point is despite the metrics it's easier to shoot in real life, at least from my experience.

[Austrasien]

More consistent drop

Absent lift or the like everything falls at exactly the same speed. And there is no significant lift or drag involved in bullet drop. Higher velocity = flatter trajectory. In the context of external ballistics, this is what "flat" means, the amount of gravity drop for a given distance of travel, which is directly proportional to the time taken to cover that distance.

[Manokan Republic]

More consistent drop

Absent lift or the like everything falls at exactly the same speed. And there is no significant lift or drag involved in bullet drop. Higher velocity = flatter trajectory. In the context of external ballistics, this is what "flat" means, the amount of gravity drop for a given distance of travel, which is directly proportional to the time taken to cover that distance.

The higher velocity results in exponentially more aerodynamic resistance, which is why the 5.56mm and .45 ACP have almost the same energy at 600 yards. The faster something travels the exponentially higher the aerodynamic resistance is, and so the more energy loss you have. To begin with the trajectory is flat, but once it starts to get out to any sort of reasonable distance it drops further than that. An example would be throwing a paper airplane as hard as you can vs. throwing it with grace. It will just crash in to the ground if you throw it too hard, but it will fly a longer distance if you throw it with the right speed.

The best example is the 5.56mm, which drops from 3100 fps, to 2629, 2205, and finally 1822 by 300 yards, or is reduced to 457 foot pounds from 1300 foot pounds, basically less than a third, in 300 yards, dropping to pistol levels of energy. While it starts off faster, it's ridiculously high speed and poor aerodynamics for that speed causes it to lose energy quickly, and in the first 100 yards you are losing 35% of the energy. In comparison, with the .45 ACP, you've gone from 343 foot pounds to 214 by 300 yards, losing only about 40% of the energy, a little under half, and it has far worse aerodynamics, only dropping from 820 fps to 648 by 300 yards, a loss of only 200 fps. The reason is a high starting velocity is an exponential problem for energy retention, and without a gigantic aerodynamic bullet, such as a tank round, isn't really feasible. Starting off at a lower velocity still results in a shorter range, but the drop off in speed is less. The bullet drop is higher, but more consistent, although in the case of the 5.56mm is still longer range than a .45, where as in comparison to a 9mm, this is less of the case. The metrics I'm using are only to illustrate the difference in the change of velocity and power, not the ballistic trajectory itself. For this and other reasons it's typically easier to hit the target with a .45 ACP.


A more reasonable comparison is the difference between the 5 grams, Mk262 .35 BC blackhills round, and the 4.1 gram .2 BC 5.56mm round. The sniper variant of the 5.56mm is actually heavier and slower, and yes it preffered by snipers because the drop is more consistent and thus easier to hit targets with, even though in theory it should have a shorter range. Similarly, the 11.3 grams 7.62mm NATO sniper round is heavier than the standard 9.7 gram NATO ball round, for much the same reason. While a less pronounced difference, it short of illustrates that going slower can actually make it useful for hitting the target, in varying degrees that drops off on both ends. Obviously it's too low of a velocity it's not practical anymore, but for a rifle round between 750-850 m/s seems more ideal, and most sniper rounds fall within this range. To get up to higher velocities, you really need a more aerodynamic bullet, with more mass or the like. The 5.56mm can get up to 940 m/s, but does so at sort of being of low use past 300-400 yards.

While subjective, it just feels better, which is kind of hard to quantify. Another example is that the .50 caliber bullet is twice as big around as the 5.56mm, and is not particularly aerodynamically shaped, having over 4 times the surface area, and it has a BC of 1.05, vs. .2 for the 5.56mm. The reason is that mass or inertia helps the round to retain it's energy better, even with worse aerodynamics. A heavy round inherently will hold on to more of it's energy at any speed, and this effect is especially noticeable when you consider how small most bullets are, like the 5.56mm is around the same weight as a nickel. So despite what you might think, the heavy un-aerodynamic thing often times retains more energy, and has less change in speed in flight, and thus, a more consistent, albeit it greater drop.

[Puzikas]

.45ACP had 98ftlb E at 600m while 5.56x45mm has 236ftlb E at 600m using 230gr FMJ vs M855A1

[Sevvania]

So despite what you might think, the heavy un-aerodynamic thing often times retains more energy, and has less change in speed in flight, and thus, a more consistent, albeit it greater drop.

None of this translates to "flatter".

While subjective, it just feels better, which is kind of hard to quantify.

That's why I don't know why you're trying to use it as a defense for your argument. Subjectively, I prefer the M1 Carbine over the AR-15. But if somebody tells me all the ways that the AR-15 is a superior gun, I'm not gonna go, "Well it's hard to quantify and directly at odds with the proven data you've provided, but you're wrong because of my own perception of reality." Because my own bias doesn't change the numbers.

[Manokan Republic]

.45ACP had 98ftlb E at 600m while 5.56x45mm has 236ftlb E at 600m using 230gr FMJ vs M855A1

My calculations were based on this.

So despite what you might think, the heavy un-aerodynamic thing often times retains more energy, and has less change in speed in flight, and thus, a more consistent, albeit it greater drop.

None of this translates to "flatter".

It does, a more consistent trajectory is flatter and less curved.

While subjective, it just feels better, which is kind of hard to quantify.

That's why I don't know why you're trying to use it as a defense for your argument. Subjectively, I prefer the M1 Carbine over the AR-15. But if somebody tells me all the ways that the AR-15 is a superior gun, I'm not gonna go, "Well it's hard to quantify and directly at odds with the proven data you've provided, but you're wrong because of my own perception of reality." Because my own bias doesn't change the numbers.

Specifically, I was referring to the ease to hit targets. It's why so many sniper rounds have lower velocities. But yes it's based on my opinion, which is what I started the conversation out with, saying it was surprisingly easier to hit targets with at long range. xP The metrics are just to show the difference in performance and not to show it has a longer range on paper.

[Sevvania]

a more consistent trajectory is flatter and less curved.

This is the opposite of when you said:

However due to it's ridiculous arc, it tends to have to be aimed up higher and thus is more like an artillery piece out to longer range which, isn't practical to aim with.

---

But yes it's based on my opinion, which is what I started the conversation out with

You started the conversation with:

The main advantage is reduced noise, a surprisingly longer range, and better stopping power.

None of which is presented as opinion, because you said "The advantage is" and not "Some possible advantages might be".

[Kassaran]

a more consistent trajectory is flatter and less curved.

This is the opposite of when you said:

However due to it's ridiculous arc, it tends to have to be aimed up higher and thus is more like an artillery piece out to longer range which, isn't practical to aim with.

---

But yes it's based on my opinion, which is what I started the conversation out with

You started the conversation with:

The main advantage is reduced noise, a surprisingly longer range, and better stopping power.

None of which is presented as opinion, because you said "The advantage is" and not "Some possible advantages might be".

Welcome to the looking glass Sev. Things get wibbly-wobbly here when you start to peer too closely.

[Manokan Republic]

a more consistent trajectory is flatter and less curved.

This is the opposite of when you said:

However due to it's ridiculous arc, it tends to have to be aimed up higher and thus is more like an artillery piece out to longer range which, isn't practical to aim with.

---

But yes it's based on my opinion, which is what I started the conversation out with

You started the conversation with:

The main advantage is reduced noise, a surprisingly longer range, and better stopping power.

None of which is presented as opinion, because you said "The advantage is" and not "Some possible advantages might be".

The reason why I said "surprisingly" was that the metrics might point to the opposite, and I also talked about other elements that were my opinion like stopping power which is harder to prove. Whether it's surprising to you will be different than if it's surprising to me so the implication is, it's my opinion. I didn't think this would need to be explained, and I'm still explaining it despite explaining it in my second post. Also I'm explaining what I mean by flatter trajectory, which is a more consistent drop, less loss in velocity. It's relative to itself, and not to a higher velocity round. A "flat" trajectory refers to, a consistent trajectory pattern, as opposed to one that shifts abruptly, like many high velocity rounds. With a higher starting velocity you may have less drop overall, but you end up with a greater variation in drop at each 100 yards.

The trajectory of all bullets is curved, and with a lower starting velocity you have to aim the weapon up at a higher angle to hit the target. But consistency in drop vs. total drop are two different things, even though the terminology may sound similiar. This can be summed up now as a matter of semantics.

[Sevvania]

A "flat" trajectory refers to, a consistent trajectory pattern

"Flat" means "not curved". At the very least, "less curved". What it does not mean is "rainbow-like" or "artillery-esque," because neither of these things are flat.

With a higher starting velocity you may have less drop overall, but you end up with a greater variation in drop at each 100 yards.

The trajectory chart shows that that isn't true. That's why the blue line is steeper than the green line.

[Manokan Republic]

A "flat" trajectory refers to, a consistent trajectory pattern

"Flat" means "not curved". At the very least, "less curved". What it does not mean is "rainbow-like" or "artillery-esque," because neither of these things are flat.

With a higher starting velocity you may have less drop overall, but you end up with a greater variation in drop at each 100 yards.

The trajectory chart shows that that isn't true. That's why the blue line is steeper than the green line.

No trajectory is actually flat, and is typically in reference to a consistent trajectory. A flat trajectory in this context refers to a consistent one. The arc of all bullets, ultimately, is curved of course. A 5.56mm will look like a rainbow if fired out to a sufficient distance, as will a .50 cal or artillery round. But the rate of decline is what I was talking about. It depends on the perspective if it's a rainbow or curved trajectory or not, for example out to 10 yards it wouldn't, or even out to 100 yards. The question is not a matter of raw steepness, and I never said it was, but at the rate at which the trajectory itself changes.

You're looking at the total drop and not at the rate of drop which are two different things. I didn't mean to imply that a .45 ACP was as fast as a 5.56mm, and I thought that was obvious. There is a difference between the total curvature of the trajectory path and the rate at which the trajectory changes.

[Triplebaconation]

A more reasonable comparison is the difference between the 5 grams, Mk262 .35 BC blackhills round, and the 4.1 gram .2 BC 5.56mm round. The sniper variant of the 5.56mm is actually heavier and slower, and yes it preffered by snipers because the drop is more consistent and thus easier to hit targets with, even though in theory it should have a shorter range. Similarly, the 11.3 grams 7.62mm NATO sniper round is heavier than the standard 9.7 gram NATO ball round, for much the same reason. While a less pronounced difference, it short of illustrates that going slower can actually make it useful for hitting the target, in varying degrees that drops off on both ends. Obviously it's too low of a velocity it's not practical anymore, but for a rifle round between 750-850 m/s seems more ideal, and most sniper rounds fall within this range. To get up to higher velocities, you really need a more aerodynamic bullet, with more mass or the like. The 5.56mm can get up to 940 m/s, but does so at sort of being of low use past 300-400 yards.

[Manokan Republic]

A more reasonable comparison is the difference between the 5 grams, Mk262 .35 BC blackhills round, and the 4.1 gram .2 BC 5.56mm round. The sniper variant of the 5.56mm is actually heavier and slower, and yes it preffered by snipers because the drop is more consistent and thus easier to hit targets with, even though in theory it should have a shorter range. Similarly, the 11.3 grams 7.62mm NATO sniper round is heavier than the standard 9.7 gram NATO ball round, for much the same reason. While a less pronounced difference, it short of illustrates that going slower can actually make it useful for hitting the target, in varying degrees that drops off on both ends. Obviously it's too low of a velocity it's not practical anymore, but for a rifle round between 750-850 m/s seems more ideal, and most sniper rounds fall within this range. To get up to higher velocities, you really need a more aerodynamic bullet, with more mass or the like. The 5.56mm can get up to 940 m/s, but does so at sort of being of low use past 300-400 yards.

The BC is higher in part due to the weight, and a high BC round at higher velocities still suffers. You lose velocity faster at high velocities exponentially so. Even a low BC round such as a .45 ACP, simply by traveling so slow, loses less energy than the higher BC 5.56mm NATO round. The comparison of higher end sniper rounds was just to show the optimum way to take advantage of that. A heavier round with the same or lower BC will still retain more of it's energy at longer range and have less loss in velocity. Already being under supersonic velocities helps as well, as when you cross the super sonic barrier it tends to destabilize the round. As the 9mm is right on the edge, this can disrupt accuracy and energy more than with, a .45.

So for hypothetical sake, I went ahead and did the calculation of a .45 ACP with 1800 joules of energy, the same as a 5.56mm, with .15 BC vs. 2 BC of the 5.56mm. The .45 ACP did lose more energy in the first 100 yards as it was crossing the super sonic barrier, but, by 600 yards it would have 242 foot pounds vs. 153 for the 5.56mm, even though the BC is actually, lower. This is due to the fact a lower starting velocity and a higher mass means more energy at long ranges, as you lose less velocity past a certain point. The loss in speed is more consistent. A real life bullet with the ballistics of the .45 shown would be something akin to a .44 magnum round or downloaded .45-70 government, albeit it's just for example and such a round in real life would be silly. A more realistic example would be a .30 carbine with 1400 joules vs. a 5.56mm from a 14.5 inch barrel with 1400 joules, to show same general effect.

So anyways, a heavier low velocity bullet will lose less energy even if it's BC is lower. As inertia by itself and the increased drag from higher velocity will impact energy retention and resultingly velocity loss. The equation for aerodynamic calculations is hideously complex, but as U, or speed, is squared, you can see that the effect of velocity is exponential. It's impact on energy loss is greater the faster the projectile goes, even if the BC is the same or in some cases, higher.

[Triplebaconation]

Your numbers are highly skewed because you're using the G1 drag model for two highly dissimilar projectiles. Don't expect them to be close to real-life results. The G1 drag model, conveniently for you, will underestimate the performance of 5.56 and overestimate .45 ACP.

Your knowledge of drag is elementary at best. Drag force is proportional to the coefficient of drag times the square of velocity. The coefficient of drag rises rapidly with velocity, peaks at around Mach 1, then falls off again.

The ballistic coefficient, of course, is inversely proportional to negative acceleration, which is what you mean (apparently) by "flatter" and "more consistent" curves. It already includes mass, so there's no need to worry about inertia or anything like that.

While subjective, it just feels better, which is kind of hard to quantify. Another example is that the .50 caliber bullet is twice as big around as the 5.56mm, and is not particularly aerodynamically shaped, having over 4 times the surface area, and it has a BC of 1.05, vs. .2 for the 5.56mm. The reason is that mass or inertia helps the round to retain it's energy better, even with worse aerodynamics.

Ballistic coefficient is literally aerodynamic efficiency.

[Republic of Penguinian Astronautia]

I love how on these threads, one sentence offhand questions can ignite pages long wall-of-text arguments!

[Puzikas]

Ballistic coefficient is literally aerodynamic efficiency.

Thanks for saying what I was going to.

I have nothing to add but the actual G7 BC is .151 and the G1 is like .349, using that you get a 600yd energy of 384ftlb using the same calculator.

E: This ofc adds that G1≠G7 since the form factors are not comparable

[Republic of Penguinian Astronautia]

Thanks for saying what I was going to.

I have nothing to add but the actual G7 BC is .151 and the G1 is like .349, using that you get a 600yd energy of 384ftlb using the same calculator.

You're welcome.

[Manokan Republic]

Your numbers are highly skewed because you're using the G1 drag model for two highly dissimilar projectiles. Don't expect them to be close to real-life results. The G1 drag model, conveniently for you, will underestimate the performance of 5.56 and overestimate .45 ACP.

Your knowledge of drag is elementary at best. Drag force is proportional to the coefficient of drag times the square of velocity. The coefficient of drag rises rapidly with velocity, peaks at around Mach 1, then falls off again.

The ballistic coefficient, of course, is inversely proportional to negative acceleration, which is what you mean (apparently) by "flatter" and "more consistent" curves. It already includes mass, so there's no need to worry about inertia or anything like that.

While subjective, it just feels better, which is kind of hard to quantify. Another example is that the .50 caliber bullet is twice as big around as the 5.56mm, and is not particularly aerodynamically shaped, having over 4 times the surface area, and it has a BC of 1.05, vs. .2 for the 5.56mm. The reason is that mass or inertia helps the round to retain it's energy better, even with worse aerodynamics.

Ballistic coefficient is literally aerodynamic efficiency.

They're close enough to be comparable for basic calculations, and I do know the difference and cited it. What I was focusing on specifically was velocity, and it's impact on increased aerodynamic drag.

The ballistic coefficient is not just aerodynamic efficiency. The drag coefficient is by itself a measurement of aerodynamic drag, or the lack there-of, and is a measure of aerodynamic efficiency in and of itself, while the BC is the ability to overcome aerodynamic drag. The Ballistic coefficient is a combination of factors, mass, cross sectional density and so on. The difference is that while BC determines an object's ability to overcome aerodynamic drag, it is not a determination of the aerodynamic drag the shape of the object will bring itself. Aerodynamic drag is dependent on a number of factors, but the shape of a projectile can influence the drag behavior, where as things like density and mass of the projectile or object can help determine it's ability to overcome the drag, but not how much drag it will receive. The distinction is important for things like cars and aircraft, and while a more efficient drag coefficient will enhance the ability to overcome aerodynamic drag, it is not the same thing, although often it's conflated. So yes mass and the like determine how efficiently a projectile can overcome drag, while the drag coefficient is how much drag it receives in the first place. Fundamentally a smaller projectile will have less drag, but they also usually have less mass, so they have a harder time overcoming the drag, even if it's less. The BC is a balance of this, which usually errs on the side of more massive projectiles having a better BC. This is due to inertia, which is directly proportional to mass (except in a few rare circumstances), or the propensity of an object to keep moving.

[Triplebaconation]

I love how on these threads, one sentence offhand questions can ignite pages long wall-of-text arguments!

The 9mm vs. .45 ACP argument is the oldest and worst there is. Handgun bullets and their associated gunshot wounds are inherently unpredictable, impossible to model accurately, and resistant to empirical study, so it will never be conclusively proved one way or another.

On the other hand, judging by its universal condemnation by lunatics in the comment sections of various popular gun sites I'd say the 9mm is probably pretty good.

The ballistic coefficient is not just aerodynamic efficiency. The drag coefficient is by itself a measurement of aerodynamic drag, or the lack there-of, and is a measure of aerodynamic efficiency in and of itself, while the BC is the ability to overcome aerodynamic drag. The Ballistic coefficient is a combination of factors, mass, cross sectional density and so on. The difference is that while BC determines an object's ability to overcome aerodynamic drag, it is not a determination of the aerodynamic drag the shape of the object will bring itself. Aerodynamic drag is dependent on a number of factors, but the shape of a projectile can influence the drag behavior, where as things like density and mass of the projectile or object can help determine it's ability to overcome the drag, but not how much drag it will receive. The distinction is important for things like cars and aircraft, and while a more efficient drag coefficient will enhance the ability to overcome aerodynamic drag, it is not the same thing, although often it's conflated. So yes mass and the like determine how efficiently a projectile can overcome drag, while the drag coefficient is how much drag it receives in the first place. Fundamentally a smaller projectile will have less drag, but they also usually have less mass, so they have a harder time overcoming the drag, even if it's less. The BC is a balance of this, which usually errs on the side of more massive projectiles having a better BC. This is due to inertia, which is directly proportional to mass (except in a few rare circumstances), or the propensity of an object to keep moving.

Please read this carefully and see if you can spot your mistakes. The wiki articles you've helpfully linked contain a few clues.

[Manokan Republic]

I love how on these threads, one sentence offhand questions can ignite pages long wall-of-text arguments!

The 9mm vs. .45 ACP argument is the oldest and worst there is. Handgun bullets and their associated gunshot wounds are inherently unpredictable, impossible to model accurately, and resistant to empirical study, so it will never be conclusively proved one way or another.

On the other hand, judging by its universal condemnation by lunatics in the comment sections of various popular gun sites I'd say the 9mm is probably pretty good.

The 9mm I would say is okay, while the .45 ACP is better. A 9mm +P round tends to help fill in the gaps, so it becomes more reasonable. A 9mm +P round can get power all the way up to a .357 magnum, so if you use such a round the power can be comparable enough not to really matter. I just prefer the .45 for a number of reasons, and didn't expect to get in to a long winded conversation about how it's easier to hit targets at 100 yards or talk about irrelevant micro-issues to that point.

The ballistic coefficient is not just aerodynamic efficiency. The drag coefficient is by itself a measurement of aerodynamic drag, or the lack there-of, and is a measure of aerodynamic efficiency in and of itself, while the BC is the ability to overcome aerodynamic drag. The Ballistic coefficient is a combination of factors, mass, cross sectional density and so on. The difference is that while BC determines an object's ability to overcome aerodynamic drag, it is not a determination of the aerodynamic drag the shape of the object will bring itself. Aerodynamic drag is dependent on a number of factors, but the shape of a projectile can influence the drag behavior, where as things like density and mass of the projectile or object can help determine it's ability to overcome the drag, but not how much drag it will receive. The distinction is important for things like cars and aircraft, and while a more efficient drag coefficient will enhance the ability to overcome aerodynamic drag, it is not the same thing, although often it's conflated. So yes mass and the like determine how efficiently a projectile can overcome drag, while the drag coefficient is how much drag it receives in the first place. Fundamentally a smaller projectile will have less drag, but they also usually have less mass, so they have a harder time overcoming the drag, even if it's less. The BC is a balance of this, which usually errs on the side of more massive projectiles having a better BC. This is due to inertia, which is directly proportional to mass (except in a few rare circumstances), or the propensity of an object to keep moving.

Please read this carefully and see if you can spot your mistakes. The wiki articles you've helpfully linked contain a few clues.

It doesn't even matter if I made random mistakes, my central point is that aerodynamic drag efficiency and total ability to overcome this drag are two different things. I'm not going to an infinite amount of detail on every topic on purpose to avoid a 16 page long wall of text, and am instead just isolating the key point I'm talking about and trying to reduce it to a more simpler form so it's obvious.

[Taihei Tengoku]

known pedant claims he is avoiding pedantry

[Triplebaconation]

It doesn't even matter if I made random mistakes, my central point is that aerodynamic drag efficiency and total ability to overcome this drag are two different things. I'm not going to an infinite amount of detail on every topic on purpose to avoid a 16 page long wall of text, and am instead just isolating the key point I'm talking about and trying to reduce it to a more simpler form so it's obvious.

I guess I'll tell you then.

The first is aerodynamic efficiency is totally dependent on context, and there's no set definition for the term. If you were talking about the aerodynamic efficiency of an aircraft, for example, you'd normally describe aerodynamic efficiency in terms of the lift/drag ratio. In ballistics, especially in the context of this discussion, you'd use ballistic coefficient, since (as you said yourself) it "determines an object's ability to overcome aerodynamic drag."

The second is that the ballistic coefficient already includes the drag coefficient, which is why you use different BCs with different drag models--hopefully the one matching the shape of your bullet the best. It's right there in your wiki article!

Larger projectiles tend to have better BCs because the square-cube law means they have higher sectional density. This is more important than overall mass. Two projectiles with the same BC and velocity will have identical trajectories regardless of their mass, at least if you're using the same drag model for both.

You seemed to grasp at least the basic principles of ballistic coefficients when you were discussing the EM-2 a few weeks ago. I wonder what happened.

[Manokan Republic]

It doesn't even matter if I made random mistakes, my central point is that aerodynamic drag efficiency and total ability to overcome this drag are two different things. I'm not going to an infinite amount of detail on every topic on purpose to avoid a 16 page long wall of text, and am instead just isolating the key point I'm talking about and trying to reduce it to a more simpler form so it's obvious.

I guess I'll tell you then.

The first is aerodynamic efficiency is totally dependent on context, and there's no set definition for the term. If you were talking about the aerodynamic efficiency of an aircraft, for example, you'd normally describe aerodynamic efficiency in terms of the lift/drag ratio. In ballistics, especially in the context of this discussion, you'd use ballistic coefficient, since (as you said yourself) it "determines an object's ability to overcome aerodynamic drag."

The second is that the ballistic coefficient already includes the drag coefficient, which is why you use different BCs with different drag models--hopefully the one matching the shape of your bullet the best. It's right there in your wiki article!

Larger projectiles tend to have better BCs because the square-cube law means they have higher sectional density. This is more important than overall mass. Two projectiles with the same BC and velocity will have identical trajectories regardless of their mass, at least if you're using the same drag model for both.

You seemed to grasp at least the basic principles of ballistic coefficients when you were discussing the EM-2 a few weeks ago. I wonder what happened.

This literally didn't contradict anything I had already said. I've made it clear that I know the ballistic coefficient includes the drag coefficient, in fact my entire point is that it's a part of the ballistic coefficient calculation, and not that the BC is the aerodynamic efficiency itself. I know that the efficiency changes at different velocities, *in fact*, that was my entire point to begin with, that higher velocity rounds will lose energy faster. Pointing this out as a mistake of mine when I literally, literally, have been talking about that the whole time is absurd. You're just trying to find some sort of hole in what I said, irrelevant to my point, to be as obtuse as possible, for basically no reason.

I also know that if the round has the same BC as the other round, at the same velocity, the trajectory will be the same even if the mass is less. The best example of this is the 6.8mm remington and 7.62mm NATO, which have very similar trajectories; the same is also true with the 77 grain, 5.56mm Black hills rounds. My point was about energy retention being different, not about trajectories, which I've stated multiple, multiple times. You will also have less loss in velocity at lower speeds, which means a more consistent drop, although total drop may be higher. A higher mass has a tendency to result in a higher BC, even if the projectile's aerodynamic drag would otherwise be higher.

[Manokan Republic]

known pedant claims he is avoiding pedantry

They just keep pulling me back in!

[Sevvania]

The 9mm vs. .45 ACP argument is the oldest and worst there is. Handgun bullets and their associated gunshot wounds are inherently unpredictable, impossible to model accurately, and resistant to empirical study, so it will never be conclusively proved one way or another.

Fortunately, "which one flies straighter" is pretty easily proven.