Warp, I am trying to get some clarification, you are trying to troll. My posts come across as argumentative, yours comes across as useless.
Murf, I initially asked this based on many, many threads where people get into caliber arguments and said "I like one or the other based on them being light/fast or slow/heavy". I wanted to know what they meant, in general, because I don't necessarily see it. I knew this would be arbitrary. If it wasn't, I could merely find the reference. But even that obviously would not exist, as terms light "light & fast" and "slow & heavy" are not going to be industry terms. I understood SD already, had an excel spreadsheet I used to generate ME and SD without going through the cells of free ballistics calculators that wouldn't let me skip the details for rifle/long range shooting.
Then two people tell me to stay within caliber for the comparison and not across calibers. I posted an acknowledgement of this, and then get lambasted by the same two people. I am now "arguing" with two people by providing examples of the exact statements they made. I have to argue with people because I tried to agree with them.
Now, to revisit the statements and see where I went wrong.
Generally, the dividing line seems to be 1000fps.
9x19mm - all light & fast, until you get to the subsonic 147gr slugs
.40 - 135gr light & fast, 180gr heavy & slow; when you get to the 200gr loads (10mm), you get heavy and fast
You don't compare them to other calibers, the light or heavy means light for that caliber or heavy for that caliber
1000 fps threshold, check
9mm and 40 S&W can be both due to the variety of bullet weights meaning you have light for caliber & heavy for caliber, check
9mm & 40 S&W can be both due to some loadings with heavy for caliber bullets also fall beneath the 1000 fps threshold, check.
What 9mmepiphany said and then some.
Although it varies with the person, the distinction between "fast" and "slow" or "high" and "low" velocities is generally held as 1,000 fps, or in some cases as above (supersonic) or below (subsonic, transonic) the speed of sound which is generally expressed as being about 1100 fps- although that figure varies with fluctuations in the temperature, density, humidity and pressure (usu. re: altitude) of the atmosphere.
As for "heavy" and "light"- that relates to the sectional density of the bullet (usu. expressed in mass per cross-sectional area) and is determined by the volume of the projectile and the density of the material comprising the projectile.
There is an equation for sectional density, too-
SD = (M ÷ 7000) ÷ (D^2)
-where M is the weight of the bullet in grains and D is the diameter of the bullet in decimal inches.
Bullets with higher sectional densities are considered "heavy", those with lower sectional densities are considered to be "light"- again the distinction blurs according to personal preference as to what is considered to be "heavy" and "light" and where the line will be drawn.
1000 or 1100 fps threshold, check.
Sectional density, check. Sectional density only goes one way if we are staying within caliber. The diameter of the bullets are all the same, since that's the caliber. You increase weight, you increase SD - as long as we are sticking to similar materials.
So again, SD equates to light and heavy for caliber, check.
I say that
So the 9mm and the .45ACP both are 'light & fast' and 'slow & heavy' at the same time? Interesting.
And I get criticized.
I provide a link. Firstly, it is obvious that when a caliber comes in multiple weights, that you will have light and heavy for caliber. Not only that, but the link shows 43 loads at or above 1000 fps. 22 of those are at or above 1100 fps. Weights listed, including frangible stuff - 255 230 200 185 175 165 160 155 145 125 115 96 90 68.
What do I get from the two who tell me that the terms are for within a caliber, for light or heavy for caliber, and that a good arbitrary number to consider is 1000/1100 fps is that I was wrong to mention .45 ACP
I didn't mention the .45ACP in my post
You did exactly what I said you shouldn't.
You took a point, about the 9mm and the .40, and applied it to another cartridge, the .45 ACP....using data that wasn't comparable (+P loadings and lighter than usual bullet weights)
Nominal loadings for the .45 ACP with 185gr, 200gr and 230gr slugs...these are all generally accepted as slow and not as slow I don't know anyone who would call a common .45ACP bullet light
I am genuinely confused by this. Slow and not as slow? How does that apply when the 'slow' velocity is greater than 1000 fps? A common bullet isn't light? A 185 gr .45, with an SD the same as a 115 gr 9mm, is not light for caliber. Even though ALL 9mm up to subsonic 147s is light & fast. Even though another common & accepted load is 230 gr and 45 gr heavier. Why? I guess 45 is slow and not so slow, and not light because it is 45. Even though we aren't supposed to look at a caliber in general and make the distinction. Again, his isn't about .45 ACP in particular. I have no experience with the cartridge. But If I then ask about 10mm, or .380 ACP, or any other caliber, am I going to be told that 1000 fps and heavy/light for caliber bullets do not apply because I am talking about the wrong caliber? Are 9mm and .40 S&W the absolute only calibers to be afforded the light/fast heavy/slow monikers?
I stay within the caliber, point out that there are light for caliber bullets going over the arbitrary threshold, and then get told I'm doing it wrong, I'm leaving stuff out, I'm lying, cheating, stealing, or something. I honestly don't know.
481, you still confuse me. I say I don't want to get into an argument over which is better. I do not get into an argument over which is better. I do not know which is better. I do not think one is all that much better than the other, since they both do the job, or fail at the job. The results are totally varied because the situations are. What I do end up having to argue about is what you are putting forth as a distinguishing line. I don't care what you think is better, and am not asking. I am asking what I got wrong when trying to follow what I considered to be exactly what you two said.
So it seems...if your objective was to find a quantitative answer
It wasn't a failure, until the quantitative answer of 1000 fps was thrown out by the very person who posted it. To say that there is no quantitative answer is fine, except that it means all the posts talking about light/fast & slow/heavy are invalid as the people who discuss it have no solid numbers in mind when they want to make the distinction. Honestly, that is what you guys did in this thread. I tried to post something in agreement to your statements, because they seemed quite straightforward. But no, we can't follow the numbers you put forth, because it was in the wrong caliber. That makes no sense when the difference is supposed to be caliber agnostic. It doesn't matter what diameter the bullet is, it only matters that it goes over/under X fps, and is either light or heavy for caliber. I will go back to thinking that the argument ties directly to 9mm vs 45, even though there is a considerable overlap in muzzle velocities and SD, since it is apparent that even to you the .45 ACP is eternally slow & heavy. Your username gives away too much.
56hawk, I do appreciate your quantitative and clear answer. I just wish the thread could have started with such direct and in line responses.
