Bullet Frontal Area Misconception

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This will not be a caliber wars thread. I am not comparing one to another in any caliber. This is to clarify a common misconception.

You will see where advocates of caliber X claim their preferred round has more frontal area over caliber Y and Z. They use a wonderful mathematical formula that takes the diameter of a bullet and "finds" the surface area and use that as fuel for their fire, because the formula shows where X is % larger than Y or Z. There is one small problem with this formula that is NOT taken into account:

Bullets are tapered toward the tip, which reduces total surface area.

Their numbers, for all their efforts, are inaccurate.
 
Uh yeah, but.....

If you take a 9mm HP vs a .45 HP, frontal cavity will still generally be bigger in the .45. I get what you're saying, but I think everyone knows what bullets look like and how they're tapered. Is there really a big misconception on this subject?

I could care less about who carries what and why. Carry what you like for your own reasons.
 
You're right. If you take into account the taper, the .45 has even MORE surface area vs. the 9mm (assuming you are talking about total surface area of the front taper of the bullet, i.e. the whole cone). Reality is, the base of the bullet still has to pass through as well.

You already had a thread closed today. Just drop it. I'm a 9mm fan myself, and even I don't care what you are saying.
 
Frontal area is taken as the projection of the three dimensional ogive shape onto a two dimensional plane perpendicular to the direction of travel. A straightforward geometrical exercise. True, it has very little to do with effectiveness, but the numbers are there.
 
Frontal area is frontal area - period. An object with a larger diameter will have a larger frontal area than one with a smaller diameter. The taper has nothing to do with it.
In fact, an object with a longer taper will have more SURFACE area, but no more frontal area.
 
I know, and agree, a larger bullet will have more frontal area. That was not the issue.

The issue are the guys who spew forth numbers and data based off what they read elsewhere, but are misinformed and inaccurate.

When trying to win a point in your favor over a debate, use supported facts, not John Doe's article from Weekly Handgunner.

Edit: what I am getting at, even though I said I would not bring it up, is that a 45 over a 9mm is NOT 61% more surface area b/c of the taper. That needs to be refigured. I will get with out forensic scientists today and see what they say and if they can give me formulas/diagrams to show the true and accurate % of frontal area a 45 has over a 9mm.

Plus they will have to do it with both FMJ and JHP to be 100% accurate.
 
OK, facts:

The formula for a truncated cone (which is what most bullets are) is:

V=1/3*pi*(R12+R1*R2+R22)*h
V = volume
pi = 3.142
R1 = Radius of the base
R2 = Radius of the top
h = height of the truncated cone

by my algebra, same as:

V=1/2*pi*(R12+R22)*h

The formula for a full taper FMJ would be:

pi*r(r + l)

For comparison, the curve of the bullet cone may be disregarded, since all will be similarly curved. The difference won't be enough to matter.

Do not confuse frontal area with surface area - they are two totally different things.
 
The taper has nothing to do with it.
Click to expand...
True, it has nothing to do with "frontal area", which to me is not the same as meplat. IMHO, frontal area has very little to do with effectiveness if the design of the bullet is not considered. In other words, I'm a big bore advocate but I'll take a premium 9mm JHP like the Gold Dot or even the .38Spl 158gr SWC/HP over .45 hardball any day of the week.
 
Quote: "The issue are the guys who spew forth numbers and data based off what they read elsewhere, but are misinformed and inaccurate.....Their numbers, for all their efforts, are inaccurate. "

It's not just the meplat/nose diameter that penetrates a target but the total diameter of the bullet. The numbers presented earlier are mathematical calculations of the two dimensional total diameter of 9mm and .45 bullets and the comparison of such diameters. You are beating a dead horse. Use whatever caliber/cartridge you prefer and be happy.
 
So,if I understand this just right ,so long as they are both sharp pointy tipped,5.56 ball is just as effective as .50 BMG ball?? Assuming they both penetrate through the target??
Thanks,I never thought of that. Wow.Learn something new every day.
 
This discussion will survive, but ONLY if it stays on topic and doesn't start breaking down into comments on individuals rather than ideas.

If anyone is wondering where his/her post went?

It either wasn't on topic, or was perilously close to being a comment on an individual rather than an idea.
 
I guess i understand what you are saying but wouldnt you just compare two different calibers with a same shaped bullet. This is pretty obvious though, you are just reducing variables.
 
Look, this is pretty simple math. A .45 has 60% more cross section than a 9mm.

A .45 has TWICE the mass as a 9mm. (115 grains verses 230 grains.)

It doesn't take a rocket surgeon to see that a .45 packs a LOT more wallop than a 9mm.

With all that said, I carry every day, as a requirement of my employment, and my carry sidearm of choice is a 9mm.

It really doesn't matter, to me, how much wallop a round carries. 4 or 5 9mm to the COM will stop anything except possible a charging water buffalo, and I don't see many of them on the streets of San Diego.

This is the real world, not a make believe scenario. My first and only question to Mr. CSI is "how many shootings have you been involved in and what was the outcome." That is the only answer that really matters. :)
 
Yeah, the only area the 9mm outpaces (no pun intended) the .45 is velocity. Total kinetic energy (which varies as the square of the velocity) is comparable (in the neighborhood of 400 foot-pounds) for both, probably a little higher for the .45 on average across a variety of loads.
 
They use a wonderful mathematical formula that takes the diameter of a bullet and "finds" the surface area and use that as fuel for their fire, because the formula shows where X is % larger than Y or Z
Click to expand...

No. As CWPinSC said, do not confuse surface area with frontal area. What I saw in the other thread referred to the latter.

I have no idea what the surface area of a bullet could possibly have to do with wound ballistics. Matter of fact, I do not know very much about handgun wound ballistics at all. I have to wonder just how there have come to be so many experts in this field.

I also wonder whether, in the pre internet and pre radio days, guys sat around the Long Branch discussing the relative merits of the .44 over the .36 Colts and Remingtons.

We know that Hickock carried the .36 and that most cavalrymen apparently preferred the .44.

We also know that the U. S. Army originally had available for the choosing both the .45 ACP and the 9MM Parabellum, and that they insisted on the former. They were choosing a gun primarily for use by the horse cavalry. Whether the decision would have been different had JHP bullets been available and permissible, no one knows, and I, for one, cannot think of a reason why it might have been.

We know that Elmer Keith was convinced that his flat bullets were more effective than round nose lead bullets. We also know that he favored .44 and .45 revolvers over smaller bores.

I will suggest that if one finds a particular gun to be difficult to learn to shoot because of noise or recoil, he or she will not find it effective. I'm better with a .257 Roberts than with a sporter-weight .30-'06. As I understand it, that is a major reason why the UK replaced the .455 Webley with the .380-200, and it would seem to mitigate in favor of the 9MM over the .45.

....but not for me.
 
"Spew forth numbers"?

The math involved is pretty straight forward. It is either accurate or not. The diameter or the radius of a bullet face is a relevant number unless we are comparing two different types of bullets, ie a wad cutter as opposed to a spire point.
 
Frontal area etc.

CSI

Your math in the related thread (now thankfully closed) is a bit sloppy. Rounding the 9mm and 45acp to 6/16 and 7/16 respectively is not valid. .452 minus .355 equals .097 which is a little better than 3/32. That beats your 1/16 by better than 50%. I'm doubting the work coming out of your lab.
 
I am going to try and stay on topic but to answer a question above...

A .355" (9mm) diameter converted from decimal to 16ths is ~6/16.
A .452 (45 ACP) diameter converted from decimal to 16ths is ~7/16.

I am at work and we are still working on exact measurements, dealing with frontal area, expansion, etc.

More later.
 
You introduce error when you convert these decimals to 16ths; 3/8" = .375", 7/16" = .4375".

Area of a circle = diameter squared times PI divided by 4. It's not difficult, how many of you are working on this?
 
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