Home Forums Hunting & Shooting Handguns ROSS SEYFRIED QUESTION

Monolithic solids pretty much destroyed the SD argument.

Without a doubt.

With a 6 shot cylinder

Monolithic solids did not destroy the SD argument, just changed the way we look at it. Unless you think a 200gr copper WFN will penetrate just as well as a 300gr??? I think we all know it won't. The only way to "destroy" the SD argument is to prove that a 200gr copper solid will penetrate the same as a 300gr, or something thereabouts. Right now all we're doing is comparing monolithics to cast bullets. This would be real easy to test by cutting the rear end off the Lehigh solids and pushing them to the same velocity.

It's more critical with cast bullets because they need more "ass" to penetrate as they deform.

To be precise, they were Sevilles with oversized six-shot cylinders.

Yes it does destroy the SD theory

Will a solid copper 300gr .500 penetrate as well as a solid copper 300gr .44? No. Would an aluminum bullet penetrate as well as solid copper? No. Mass and momentum are still factors. Mass relative to diameter is still important. Therefore so is the number that represents mass relative to diameter, which is sectional density. Not a whole lot of analytical thinking going on here.

Interesting conversation going on here and I'm enjoying it.

Same!
I know just about zilch about revolvers, but I feel like I'm learning good stuff here.

+1

Will a 500L 525 grain WLN penetrate farther than a 450 Punch Bullet? If not then SD is BS. I can assure that it will not. SD does not take into account for bullet construction, nose shape or meplat size all of which effects penetration.

How long it takes you is up to you, but id be sure you are laser accurate if you are shooting at a high trophy fee animal. Yes you can load out bullets in 45 colt cases, but then you face worse bullet pull issues. Then again, you shouldnt be using cast bullets in this scenario.

Yes, you are right. In fact we saw first hand a 400 grain ceb at 1720 fps handily out penetrate a 440 cast at 1880 fps. And a 500 cast at 1680 fps. The 500 grain was demolished the 440 held together very well. Infact the bigger faster 500 smith hardcasts didnt even penetrate better than a simple 330 grain lehigh monometal at mid 1350’s or so from a 480 ruger. These were test loads for buffalo bore dangerous game loads. The faster 300 gr 454 lehigh and ceb loads cut thru the waterbuffalos without a problem. The 460 is simply ridiculous.

Whether something is a factor is one thing, whether its worth talking about is another. The only way one could predict whether a 300 grain 500 or a 300 grain 44 will penetrate more is to have any clue what belocity of the bullets in question. I wouldnt assume the 44 would outpentrate based on sectional density. Could it play a role? Perhaps. But the material if its the same to handle the one with faster velocity, then the nose profile is huge, and the velocity is a huge determiner.

So.....in a nutshell i would bet big money i could run a 300 grain 50 cal out of a jrh case that would out penetrate a 300 gr 44 mag. The velocity of the 500 will handily outpace that of the 44. The sectional densities are so close in all the major calibers normal bullet weight. I.e. 300 to 360 in 45 and 265 to 300 gr in 44 and so forth up the chain that its a moot point besides obviously silly comparisons. The fact they are monometals means the limits velocity plays on the whole situation is now gone. Which is why i can punch thru things handily with a 300 gr 454 monometal that i cant with a 475 with cast buklets. So basically we can eliminate all trivialities in saying that a 480 ruger outperforms a 454 let alone a 460. Which wasnt a horrible observation when we were dealing with the limitations of cast bullets. This shouldnt be alarming to anyone despite the nashing of teeth from the cast purists. It opens up revolvers to perform at levels not seen before. Who wouldve guessed we could drive through bone and then thru a whole animal and then more bone better than we ever could before and we dont need ultra heavy maxed out rounds and can get by with a lighter lighter recoiling round out of everyday calibers than ever before. And we havent even talked about the biggies pushing ultra reliable expandables that provide the same offside pentration wrecking the vitals with wound channels several magnitudes larger than any of the solids. On another forum a friend of mine posted a picture of an entire lobe of a lung blown out of a deer with a swift aframe load from a 460. Hell, i put down a cape buffalo where he stood at 150 yards with a 460 and a swift aframe. Despite its rather unimpressive sectional density and expansion to .7”!

You guys are mixing way too many variables and making conclusions based on too little information.

First and foremost, the fact that a lighter monolithic outpenetrates a heavier cast does not "destroy" the SD "argument". All it means is that weight moves down the totem pole in favor of a bullet that does not deform.

Second, SD is not an all-encompassing belief system. It's not an argument. Or a measure of lethality. It is simply the bullet's weight relative to its diameter. It is a singular factor among many. I don't know why people are in such a hurry to dismiss it.

We have tons of cast bullets in various weights, so it is easy to determine that heavier bullets of a comparable shape/hardness/toughness will penetrate deeper than lighter ones. However, there are far too few monolithics to be able to even properly compare them and determine what role SD plays.

I would just about bet the farm that a 300gr .500 wouldn't come close to a 300gr .44 in penetration. I've seen this first hand with the additional drag a .45 bullet has over a .44 at a given weight. It will be interesting to find out.

You guys don't think thee's a reason why these bullets are as long as a heavy cast? If weight relative to diameter was not a factor at all, they'd be making these bullets a lot lighter, that could be driven a lot faster. But they are not.

Here's the 270gr Punch, 300gr Punch, 300gr Barnes Buster compared to 330gr LFN and 355gr WLN. If weight doesn't matter, why are they so long???

You guys carry on,tomorrow me & some friends will be blasting Rock Chucks, Ground Squirrels & hopefully a large Badger than ran across the road today. I'll be use cast & I don't expect anything to charge or need a second shot. And I can make a 50 round box of 327 bullets for what one of those first 2 bullets cost.

Dick

Agreed. SD has never been accurate not even in rifles, bullet construction, is far more important as is meplat size and nose profile.

Sectional density is the ratio of an object's mass to its cross-sectional area with respect to a given axis. It conveys how well an object's mass is distributed (by its shape) to overcome resistance along that axis.

Sectional density is used in gun ballistics. In this context, it is the ratio of a projectile's weight in pounds to its diameter in inches squared, with respect to a given axis. It conveys how well an object's mass is distributed (by its shape) to overcome resistance along that axis. For illustration, a nail can penetrate a target medium with its pointed end first with less force than a coin of the same mass lying flat on the target medium.

During World War II bunker-busting Röchling shells were developed by German engineer August Cönders, based on the theory of increasing sectional density to improve penetration. Röchling shells were tested in 1942 and 1943 against the Belgian Fort d'Aubin-Neufchâteau[1] and saw very limited use during World War II.

Contents
Formula
Edit

General
Edit
In a physics context sectional density is defined as:

S
D
=
M
A
SD={\frac {M}{A}}[2]
SD is the sectional density
M is the mass of the projectile
A is the cross-sectional area
Ballistics
Edit
In a ballistics context sectional density of circular cross-sections is most commonly defined as:

S
D
=
W
l
b
d
i
n
2
=
W
g
r
7000
d
i
n
2
{\displaystyle SD={\frac {W_{\mathrm {lb} }}{{d_{\mathrm {in} }}^{2}}}={\frac {W_{\mathrm {gr} }}{7000\,{d_{\mathrm {in} }}^{2}}}}[3][4][5]
SD is the sectional density
Wlb is the weight of the projectile in pounds
Wgr is the weight of the projectile in grains
d in is the diameter of the projectile in inches
The sectional density defined this way is usually presented without units.

As an example, a bullet 160 grains in weight and a diameter of .284 inches, would have a sectional density, SD = 160/7000 × 1/.284^2 = 0.283

Historical background
Edit

For historical reasons, within the field of ballistics it is often assumed that the unit of mass is the pound, and the unit of length is the inch. For example: ".357 magnum" (not ".357 inch magnum"). By fixing the units, quantities can be treated as dimensionless.

Use in ballistics
Edit

The sectional density of a projectile can be employed in two areas of ballistics. Within external ballistics, when the sectional density of a projectile is divided by its coefficient of form (form factor in commercial small arms jargon[6]); it yields the projectile's ballistic coefficient.[7] sectional density has the same (implied) units as the ballistic coefficient.

Within terminal ballistics, the sectional density of a projectile is one of the determining factors for projectile penetration. The interaction between projectile (fragments) and target media is however a complex subject. A study regarding hunting bullets shows that besides sectional density several other parameters determine bullet penetration.[8][9][10]

Only if all other factors are equal, the projectile with the greatest amount of sectional density will penetrate the deepest

https://en.m.wikipedia.org/wiki/Sectional_density



Notice the last sentence “Only if all other factors are equal, the projectile with the greatest amount of sectional density will penetrate the deepest”
That would include velocity.

I'm fairly certain we already knew that SD was the weight relative to diameter.

If SD doesn't matter then weight doesn't matter and we all know that weight matters.

It's bad when we start quoting Wikipedia. If we're going to get technical:

"Sectional density is the quotient of bullet weight in pounds over the diameter in inches squared.

SD = Wt/D^2.

That’s not a ratio. It’s a quotient. And diameter isn’t in the numerator, it squared is the denominator."

Once again, I have never made the argument that SD is the only important factor. As I said above, it is one of several important factors.



Pretty sure that's what I've been saying all along. I'm also fairly certain that my suggestion of cutting the rear end off a Lehigh WFN would prove or disprove the theory.

This piece below was penned by Michael McCourry, the gentleman who designed the CEB solid. He has killed more bovines in testing than anyone else I know by a wide margin to test his designs and theories. He knows what he is talking about...



There are 8 Absolute Known Factors for Solid Penetration and are as follows in
Order of Importance.....

#1 Meplat Percentage of Caliber
Meplats that attain 65% Meplat of Caliber are terminally stable.... Above 70% Meplat
bullets remain stable, however depth of penetration begins to decrease with every step up in
meplat size. 70% Meplat or larger does increase trauma to, and destruction of tissue. 70%
Meplats start to get difficult to feed, even in Winchester M70s...... From 65% Meplat to 68%
Meplat is OPTIMUM for Stability, destruction of tissues, and feed and function in most quality
rifles..........

#2 Nose Profile
There are many and varied Nose Profiles of solids on the market today, from the angled
Nose Profiles of CEB and North Fork, to the straight nose profile of the older North Forks
and GSC, the Barnes/Hornady Profiles (like a RN cut off at the top) to many more... Not all
of these are created equal, and some are better performers than others. In recent tests in
comparison between the old North Fork Profiles and the Newer North Fork Profiles I was
getting 20% deeper penetration with the Newer North Forks than the older, with the same
bullet, just difference in Nose Profile is all.... John at North Fork agrees, and in their work
there they were getting more along the lines of 25% deeper penetration. One major thing
that I noticed here, the stability at the end of penetration was 100% better. In most all tests
here the last 2 inches of penetration of the old style North Forks would be unstable. Now this
is and was of no consequence at the very end of penetration. The depth of penetration of
these older nose profile bullets was always so deep that it had long accomplished its mission
before loss of stability right at the very end. This new NOSE PROFILE of North Forks remains
DEAD STRAIGHT to the very last of penetration, and always found NOSE FORWARD........

#3 Construction & Material
Construction of a solid is a major part of its ability to penetrate. To deny this is foolish to say
the least. Some of our solids out there, lead core, are very very weak in construction and
absolutely do not have the ability to bust through heavy bone and reach their intended
targets. I have seen and have in hand failures of these bullets from the field..... A shame as
well, as some of these bullets are promoted as Dangerous Game Solids, and some of them
flatten out like pancakes when hitting some heavy..... Some FMJ Have steel inserts, while this
solves a problem in one area, it creates problems in other areas.... Brass is harder than
Copper... No surprise there, but I have busted elephant heads with both copper and brass,
and never had one distort, but, these solids were of a very STRONG NOSE PROFILE as
well........ So you see, combinations of different factors work together to strengthen or
weaken other factors..... A good strong Nose Profile, can overcome some material
deficiencies and in the case of copper solids this is extremely important, and very true........

#4 Nose Projection
Nose Projection above the top bands was the last factor discovered. There may be more
factors, but currently they remain undiscovered at this point in time.... We found that nose
projection above the top of the bands of current CNC monolithic bullets is very important to
depth of penetration. Some bullets designed to work through lever actin riflers require a
SHORT NOSE PROJECTION in front of the bands so that they can be loaded deep enough to
work through the actions of these guns... Nose Projection of these same bullets for bolt guns,
single shots, and double rifles are longer, from .600 to .700 in front of the top band. The
LONGER NOSE PROJECTION solids will penetrate on average 25% deeper than the shorter
nose projection. Now, these bullets already have all the other required factors for stability,
nose profile, construction and radius, so it is ONLY DEPTH Of penetration that is effected with
properly designed bullets.

#5 Radius Edge of Meplat
We found that the radius edge of the meplat made a difference, small, but a difference none
the less. A nicely radius edge penetrates about 5% deeper, and has more stability at the end
than a sharp edged radius.... No more to go into here, thats it.......

All the Above Factors Deal with Bullet Design........

#6 Velocity
Velocity is a factor, but it also goes hand in hand with Nose Profile and Construction/
Material. If we assume that the Meplat is optimum, the nose projection is optimum, and the
bullet has a nice radius then velocity becomes a factor in combination with nose profile and
construction/materials. Different Nose Profiles react differently with velocity. Some nose
profiles at very low velocity cannot maintain stability, but this would be in the extreme, and
other factors may come into play with some of this. In essence with some Nose Profiles,
added velocity will equate to added depth of penetration, and of course trauma and
destruction of tissue. Some nose profiles react better than others, but if properly designed,
then all will get some gain from added velocity, UNTIL you reach the point that you get
distortion of the meplat by TOO MUCH VELOCITY. Once you begin to distort that meplat,
then all sorts of strange things begin to occur. One is depth of penetration will decrease,
stability will decrease as well....... Normally you will only get this at extreme velocities at
2700-2800 fps or more, which in our big bore rifles is somewhat extreme.......... Lead core
bullets will be effected in a serious manner at extreme velocities, followed by copper, and
then brass........ Nose Profile and Construction & Material are very important for Factor
#6.........

#7 Barrel Twist Rate
Barrel twist rate really only becomes a factor when Factor #1 is DEFICIENT....... If the meplat
of caliber is undersized, less than 65%, then faster twist rates WILL INCREASE the depth of
penetration by increasing the stability of terminal penetration. A 65% Meplat of Caliber can
stabilize in slower twist rates of 1:18, or even slower...... I have seen 65% Meplat of Caliber
stabilize with ZERO TWIST....... I have seen 50% Meplat of Caliber stability increase with
faster twist rates, and have documentation to prove it, several times...... If you are using a
properly designed Solid, then twist rate becomes less important, and more important if you
are not using a proper designed solid. Fast Twist Rates can also increase stability of even RN
Solids of decent design, hardly anything can increase stability of a more pointy RN FMJ.......

#8 Sectional Density
Sectional Density will ONLY BE A FACTOR with two bullets that are exactly the same in every
other Factor or aspect. Factors #1 and #2 far outweigh Sectional Density in the terminal
performance of Solids. We can take a properly designed 458 caliber 325 gr Solid and far
out penetrate in depth and stability a poorly designed 550 gr 458 caliber bullet....... My son
recently shot a medium sized elephant at 10 yards, perfectly executed side brain shot, with a
350 gr .474 caliber properly designed solid at 2200 fps. This bullet exited the head on the
far side and still may be going for all I know. A 350 gr .474 caliber bullet has a sectional
density of .223, and I personally would choose this little 350 gr bullet over the Woodleigh
500 gr RN FMJ at .4725 (ones I have here) any and every day for any mission............

These are undeniable facts, and can be proven over and over and over again in all test work,
and these factors have been exercised in the field and have proven themselves in the field,
many many times over...... These are the 8 Factors of Terminal Penetration of Solid
Bullets.................