HOw did the SD of .300 become the "#"?
Why dont' they take into consideration the constuction of the bullet wiether lead or mono.
I have shot 500 grain bullets that are better SD than a 450 yet the 450 out penatrates the 500.

Is it safe to say that flat nose solids penetrate twice the amount of softs given the same velocity and starting diameter?

I would guess a S.D. of .25 flat nose solid should penetrate the same as a .3 soft given the same starting dia. and velocity.

A call for RIP's iron buffalo and more penetration tests!

Is there a way to measure or use some sort of mathmatical figures to compare soft vs solids?
This would make all equal for comparison.

Doug,
IMHO - SD only applies, as we think of it, to jacketed bullets, either SP or solids. It is MY opinion that monometal bullets can be .02 or more lower SD, due to materials.

It only applies to "conventional" bullets.

why is it "the" number? it is a threshold number, as conventionally BONDED bullets tended to not fragment at the "other" number of 2400fps ..

It is a cross applied materials observation that bullets up to .25 generally fragment at conventional speeds.... and .300 or higher don't tend to tear apart.

a 500 jeffe with a 535gr bullet GENERALLY tears apart sooner than a 600gr bullet, of the same design.

and by observation, bullets at "normal" speeds, .250 or so bullets tend to provide explosive kills, and .300 or more tend to penetrate deeper...


a 220gr RN .308 at 2500 CERTAINLY goes deeper than a 150gr at 3000...

jeffe

Doug,
Just get the SD in the range of .275 to .300 and acheive over 4000 ft-lbs with a monometal FN solid and you will have a legal DG cartridge anywhere, for buffalo , rhino, elephant, hippo, lion, etc.

Even though there are no legal restrictrions on Sectional Density, there are those that raise their noses at light for caliber bullets in DGR's.

Some turn their noses up at velocities under 2100 fps also. And any SD shortcomings must be offset by velocity in some minds.

SD is more important for penetration than velocity in bullet trap or live game, jawohl, but there is some room to play with increased velocity and decreased SD with any tough bullet, soft or solid.

The higher the velocity the better with a tough FN solid and a tough softnose bullet too, as long as you don't turn the bullet inside-out.

As Jeffe says, the internet arbiters allow you to give up .02 to .025 on the SD with the monometals, as a place to hang our hats.

(.275/.301)x475 = 435.4 grains
(.280/.301)x475 = 441.9 grains

Anything in the 435 to 475-grain range would be acceptable for penetration and whomp given the restraints of length and pressure in a lever action. And of course you could go heavier with the shorter lead-core than the monometal copper or brass FN.

Don't pay too much attention to mrlexma.

.475 Turnbull: Can you get 4000 ft-lbs with a 440 or 450-grainer of .475 caliber? I saw that you were getting over 5000 ft-lbs. with a 375-grainer at 2550 fps (5416 ft-lbs). Sounds like a cinch.

Macifej of S&H 2-bore could make the bullet for you if North Fork or GSC don't have it.

www.2-bore.com

Doug,
I think SD is a great way for armchair balistions to compare how a bullet might perform. I think the bullet construction and design as in the new cup point solids has a bigger impact on performance than SD.
I do recall seeing you standing over a very dead buff who didn’t know he had been hit with a bullet of marginal SD.
Bill

475 Turnbull: Can you get 4000 ft-lbs with a 440 or 450-grainer of .475 caliber? I saw that you were getting over 5000 ft-lbs. with a 375-grainer at 2550 fps. Sounds like a cinch.

Yes I can get a 450 at 2050-2100FPS with out problem. Recoil is not uncomfortable. Shot the 2 buffalo with these loads and worked great. They can be run up to a ft-lb energy of about 5000#'s but the recoil get up there too.

I can get North Fork to make one from 420 up to 475 and get them to feed properly. I could even get one at 375-400 and run the velocity up to 2400-2500 fps. I know these will also hold together at those velocity too.

Some want the velocity and some want the weight. Yet the bullet will not fall apart like a jacketed bullet will.

This has been a real interesting adventure in building a new cartridge. Doing tests, pressures, bullet/case OAL, how it will feed, what to do about bullet design. Very fun and educating too.

The .475 Turnbull with a 450-grainer at 2100 fps gives 4405 ft-lbs.

Set that as the standard factory load and it is LEGAL for any DG anywhere.

Not only legal, but works on buffalo, is handy and lightweight, and hotrodders can take it up to 5000 ft-lbs to get their jollies.

That ain't no extended-pinky-finger gun! I want one as soon as I get finished with this .395-caliber business. By then it should be available mass-produced by Winchester, with brass by Hornady, eh?

SD = 0.285 with a North Fork CUP Point and FP Solid, .475 caliber, 450-grain bullet.

Alf!

Of course - you are correct but the point of assigning static values whether they be ballistic coefficient, sectional density, or whatever is that they are relative values and provide static summary of static data in a relational database. Change a velocity or a material and the values change.

In short, the numbers we all refer to differentiate pig vs dog vs cow not the genetic code of each. All we really want to know is what kind of animal we're lookin' at NOT the square root of the specific heat of Idaho potatos during a northern hemisphere solstice in the Chinese year of the pig.

Your post might belong in the philosophical semantics forum don't ya think!

Ditto Mac. What Alf is saying is that the 450-grain .475 FP and CP at 2100 fps or faster are indeed the cat's meow in a Winchester 1886. It's a forgone conclusion already proven by Doug Turnbull.

Well said ALF, but you have given more detail than is needed. We are talking about DG bullets, which are of fairly uniform (or uniform enough) design and shape, the classic categories being:

1. Full metal jacketed solids - steel or some other heavy metal jacket over and around a lead core.

2. Cup and core soft points. Gilding metal jackets over a lead core.

3. Bonded core versions of Items 1 and 2, where the lead core is soldered or chemically bonded to the jacket metal.

4. Monometal copper or brass "solids".

5. Monometal copper or copper alloy soft points (or hollow points), some having a lead core either forward, aft or both.

That's throwing a lot of eggs in one basket, but so be it. You will note that there are no ICBM warheads or torpedoes in the basket.

Point three hundred or higher sectional density has become the standard for projectiles of this kind used for DG or heavy game, because given their (1) design and shape characteristics, (2) velocities and (3) expansion parameters (or lack thereof) - and notwithstanding relatively minor variations in construction and materials - it has been shown empirically that they will achieve optimum penetration when heavy enough to achieve an SD of .300 or higher.

Can the SD be knocked down a couple of hundredths for monometals? I would say, based on empirical evidence, that the answer is yes, but I would not want to push my luck on that one. Can velocity be relied upon to offset a low SD? I would say, again based on empirical data, that the answer is again yes, but only to a point of diminishing returns, and even at that point the returns are slim.

Note the emphasis on empiricism, rather than theory. Talk is talk and is generally cheap. Only when the bullet goes through the beast do you have something worth analysis and discussion.

Mr. Turnbull,
Nothing has been said about twist here.
What twist does the .475 Turnbull use?

Of course the 450-grainer has a higher gyro-stability factor than the heavier bullets of the same construction, in your barrel, whatever the twist. Not that this aids in target penetration, but it does not hurt the stable transition from air to target.

I have been using 1-20 but found that the longer bullets 500 lead, 450 mono's are not as accurate as the shorter lighter 325 and 400 lead, 375 mono's so I changed to 1-18

Using the 325 lead pistol bullets and the 375 Barnes shortened and lightened to 350gr. I had shot 3 groups at 300 yrds off a bench with iron sights. They all were is a 5.5" group. The heavier bullets were not a accurate 9-12" groups 450 monos' and 500 gr. soft points.

is MPG a valid measurement for an all eletric car?

Nope

How about "gas mileage" for a diesel?
Closer, but not, as the correct measure is MPG..

the formula for SD assumes a jacketed bullet, period, around a lead core, as it uses an assumption for SG.

there needs to be either a new threshold (easier to be accepted) of .275 OR a new formula to get to .300 (kinda dumb) to apply to monometal solids.

So, here's the "deal" ...

take a bullet shape, assumed RN, and conventional construction (jacketed) ..

and measure the shape (defined by formula) and length, and produce the same profile and length in a monometal (copper is good) bullet, and it will weigh less, yep.

there is little point in a LONGER bullet, if one "spots" (gives) .025 to the inherently LIGHTER material.

Sort of as stupid as saying "leading" with a barnes solid... you MEAN copper fouling...

Is there a way to figure the volumetric weight of lead, lead copper jacketeed, all copper bullet to put into the equation to make things equal?
I am not smart enough to figure this but I am sure some one is able to come up with the formula to do this so every one can.

Doug -

Let Jeffe do it!! He has all kinds of degrees and certificates in things we can't spell or understand!!

I'd do it but I'm out of Ratzeputz and can't do multi-variate matrix work when I'm drinking fox piss like Bombay Sapphire!

SD is SD no matter the "volumetric density" of the bullet material or its construction.

The "Old Rule of .3 SD" was applied to "old bullets."

It is just a simple empirical observation from over a century of field experience by millions, simple and true. So stupidly simple that it is smart.

You need a "new rule" with the new monometal bullets that are longer and "harder" for any given SD, whether HP-soft or FN-solid, and of better weight retention with the HP-softs and less deformation and straighter tracking with the FN-solids. And the new bullets have to be slightly lighter to stabilize as well in the old twists as the old bullets did. And the new bullets can go faster and handle the extra speed well too.

Just that simple and not so stupid.
"New rule of .275 SD."

Copper specific gravity = 8.95
Lead sp.gr. = 11.34

Copper is 78.9% as dense as lead.

.275 SD for "new rule bullet" is 91.7% of "old rule bullet" SD of .300:

New bullets seem to gain more in relative effectiveness than the 8.3% of weight that they give up by virtue of their greater structural integrity or FN nose factors.

Just a new rule, just as simple and wise as the old rule.

But if you have a fast enough twist and enough case capacity, there is still good use for monometal bullets of .3 SD and a bit more.

That's enough numbers.

To Doug, and the others, I can say that in my 450 No2, shooting elephants in the head, the North Fork FP does penetrate quite a bit deeper on frontal shots than the 480 Woodleigh Solids.

In your 475 Turnbull Lever I would prefer the heavier bullet for solids on the BIG stuff.

I can say that a Buffalo Bore 420gr Cast bullet from a 6" 475 Freedom Arms will penetrate to the brain of an elephant from the front or side.

I see no reason why your 475 TB with the North Forks would not do as well.

Obviously, the .475 Turnbull with 450-grain bullet of .285 SD is adequate for DG with "New Rule Bullets" like North Fork CP and FP.

It makes a pretty good varmint and PG rifle with the lighter bullets like 375-grainers at 2550 fps.
Quite versatile, and accurate out to 300-yards. That about covers it for a one rifle hunting battery.

Mr. Turnbull:
Can you not put a Scout Scope on one of those 1886 models? You got anything against scopes other than puritanical nostalgicism?

The Berry-Smith SD formula modification:

For monometal, brass or copper, the threshold value for appropriate SD may be reduced up to and including .025 to compare with conventional bullets. Alegorical evidence of bullets of this construction "penciling" (acting as solids) confirms this supposition.

quote:

Originally posted by jeffeosso:
The Berry-Smith SD formula modification:

For monometal, brass or copper, the threshold value for appropriate SD may be reduced up to and including .025 to compare with conventional bullets. Alegorical evidence of bullets of this construction "penciling" (acting as solids) confirms this supposition.

The "BS Rule" of SD. I love it!
Finally some meaningful BS.

You should not be making rules about SD and monometal bullets. Monos do not care what rules you make about SD, they work regardless and often contrary to SD rules, just to make a point.

Make all the rules you like about SD and heavy metal bullets. We will just sit on the sidelines and snigger up our sleeves.

Word from the GSC Man who coined the phrase "New Rules" for his HV and FN bullets: Gerard

No doubt the North Fork FP and CP are strong work inspired by GSC.

Barnes made a weaker effort with their TSX and "Banded" solid.

New Rules can apply to SD too. We all snicker a bit about any SD rules now.

I am doing the water-torture-test on the .395/340-grain GSC HV prototype this weekend. SD = .311
We have enough twist and velocity.

The initial question of this thread hints towards the question of penetration depth. Penetration is governed by force over drag. Therefore Mo/Xsa is a much better measure than SD on its own. Without forward motion SD cannot guide us, as it has no momentum value attached to it. Momentum traps bullet mass and velocity. SD is only a ratio, and could be misused and misapplied very easily when not used in the proper context. SD still features in the above formula, and is still at work as Alf says; just in a disguised way. For example, just picking a bullet with a higher SD does not tell the full story as to its application:

.375"/300 gr bullet ----- SD = .305
.510"/535 gr bullet ----- SD = .294

It should be clear that without bullet mass, we are still in the dark, and even if we have the bullet's mass, we still need to bring the bullet into motion (velocity). At this stage we have a fair idea of performance with non deforming solids, but if we consider the shape of the tip (Pointed, RN or FN) we can optimizse bullet behaviour further. Even increased velocity achieves diminished returns after a certain point due to increased stagnation pressure.

With deforming bullets, bullet behaviour is even more complex. Now we have to consider the construction of the bullet, as to how it will expand, and at what velocity threshold it will start to fail (under expand at too low a velocity, over-expand at too high a velocity, and weight loss/shatter characteristics)

Also, penetration is but one aspect in killing, the size of the hole is another one in the equation. That is why a .264"/160 gr bullet or a .284"/175 gr bullet is not preferred over, for example, a .375"/300 gr bullet when headshots are to be taken on elephant.

Warrior

Here is classical comparison of where a .458/500 gr bullet that features a higher SD (SD = .341) penetrates less than a .423"/400gr bullet with a lower SD (SD = .319). The higher SD bullet in this example also carries with it a higher momentum value. The answer lies in Mo/Xsa, as the cross sectional area is the factor that inhibits penetration, the bigger it gets.

458 Win Mag (500 gr @ 1,900 fps) --- Mo/Xsa = 646 [135.71/.210]
404 Jeffery (400 gr @ 2,250 fps) ------ Mo/Xsa = 718 [128.57/.179]

The value of SD lies in the same caliber when you have to make a decision as to what bullet weight you seek for a given application.


Warrior

Let us compare some calibers at classical factory velocities and assume we use solid bullets to avoid some of the imponderables mentioned earlier; the Mo/Xsa is quite indicative of penetration ability provided we shoot the same bullet in all of them.

458 Win Mag (500 gr @ 1,900 fps) --- Mo/Xsa = 646 [135.71/.210]
404 Jeffery (400 gr @ 2,250 fps) ------ Mo/Xsa = 718 [128.57/.179]
375 H&H (300 gr @ 2,500 fps) --------- Mo/Xsa = 760 [107.14/.141]
338 Win Mag (250 gr @ 2,650 fps) ---- Mo/Xsa = 830 [94.64/.114]

Very few bullets, if any, will out penetrate a .338 bullet.

Warrior

Alf,

Please elaborate on your statement of ... "they contribute nothing without considering what the bullet does in target."

Also comment on what would happen if we use the above loads with FN Solid bullets in flesh, the size of say a buffalo on a side-on shot, or even in ballsitic gelatine, because I am just talking about the principle as a comparative guide. My guess is that they would all exit the buffalo in a straight line, provided they are not deflected by bone and tumble, given the standard twist rates that these calibers are coming out with. The comparative bullets should be the same right through.

I accept that in-target drag can differ, but how do we measure in real life when every shot into an animal is unlike the previous one?


Warrior

sigh.. this is confusing several disciplines again.

oglong shapes are more stable than round, and are NOT inherently unstable ...

DRAG has NOTHING to do with accuracy, zero, zip, nada, otherwise wadcutters wouldn't be the most accurate bullet shape for pistols...

However, mercedes found that there is a partical limit to oblong shapes reducing drag, and anything more is just wasted, to the point of being determential due to weight...


so, back to the Berry-Smith ... SD of .275 is more than good enough for copper based monometal bullets to perform like a jacketed bullet... the end

quote:

so, back to the Berry-Smith ... SD of .275 is more than good enough for copper based monometal bullets to perform like a jacketed bullet... the end

So this means the hard cast 405's @ 2150 fps with 4,000 fpe from a 45-70 in a ruger #1 qualify for DG correct?
www.cpcartridge.com sells these loads

that makes the 450 and 50 Alaskan DG carts from lever actions.

The 500 grain 50 Alaskan going 1,900 fps breaks the 4,000 fpe barrier.

With a maxed out oal Marlin the 45-70 can do this with hotloads.

And the 475 turnbull needs to throw his 425 graines @ 2060 fps

Not optimal but with non deforming flat nose bullets the formula qualifies these.

I guess they figured this out with the 405's in the 1800s

I had to head shoot a fallow with this 123gn KJG 308 bullet and retrieved the bullet which had buries itself 20 cm into the clay. Weight retension was 78%
The reduction in SD after fragmentation was 23%. Using some 150 gn retrieved lead bullets which expanded @ 1cm the reduction in SD was 85%. This calculation shows how the hollow point momnmeteal family of bullets can penetrate extremly deeply for a light for caliber bullet.



PS I know this is not accurate mathematical data and is horribly impirical but it serves as an illustration

Mark

Alf,
That rifles don't use wadcutters. OH WAIT A DAMN MINUTE ...
sure they do, alf ... the large meplat, flat nose solids, aka Bridgers, which are AMAZINGLY accurate, are nearly wad cutters, especialy if compared to 1.5E round nose bullet (1.5 diamter in length) ...

You don't see lots of big bores being used today.. EXCEPT IN BLACKPOWDER .. with giant flatnosed bullets..

quote:

Originally posted by ALF:
I did not state that drag inferred accuracy, please show me where I did?

quote:

Originally posted by ALF:
..... we need it to travel over distance with the least amount of drag and show consistant point of impact.

A sphere is WHAT in flight? Sir, put a round ball in a muzzle loader .. without rifling, your max accurate fire is 60 yards (brown bess).. add rifling and it helixs at high speed, but it acceptable to what, 80yards?

put a conincal in EITHER and you triple the range.

Jesus, Alf, physics 101 tells you that a sphere is the WORST natural shape to go though air ... that's why planes aren't spheres ... highest surface area to mass POSSIBLE.. this is a square/cube law issue ...

IF round balls shot better, we would all be using them... and tanks wouldn't use sabots (no twist) ...

Alf, I respect you alot, but you aren't making alot of sense op these. Have fun with this, I am finished discussing this with you

SIGH ... boomy ... COPPER BASED ... lead doesn't need to apply

quote:

Originally posted by boom stick:

quote:

so, back to the Berry-Smith ... SD of .275 is more than good enough for copper based monometal bullets to perform like a jacketed bullet... the end

So this means the hard cast 405's @ 2150 fps with 4,000 fpe from a 45-70 in a ruger #1 qualify for DG correct?
www.cpcartridge.com sells these loads

that makes the 450 and 50 Alaskan DG carts from lever actions.

The 500 grain 50 Alaskan going 1,900 fps breaks the 4,000 fpe barrier.

With a maxed out oal Marlin the 45-70 can do this with hotloads.

And the 475 turnbull needs to throw his 425 graines @ 2060 fps

Not optimal but with non deforming flat nose bullets the formula qualifies these.

I guess they figured this out with the 405's in the 1800s

good hard casts act as non deforming solids at lower velocities...

Granted copper, bronze, brass ect are better.

spherical planes

it would take a lot of power to push a fn 1,000 yards in the accuracy velocity envelope.

Does not the turbulance of a poor bc bullet affect accuracy in a big way???

The concept of reduction of SD from its pristine condition should not be seen as a negative thing. Controlled expansion bullets are designed to do just that; ie to expand its petals and to become shorter and thereby remain more stable and head-on and at the same time to make a bigger hole. We should actually look at how high SD bullets perform in the terminal process of expanding its Xsa and thus reducing its terminal SD. Here is an example of a 9,3 mm/286 gr Rhino bullet retrieved from a Hippo:



I much prefer bullets that retain most of their weight, and keep their petals intact, as opposed to the type that are "light-for-caliber" and lose their front section like the KJG type that MarkH posted, as they shed their petals at high impact velocity within the first few inches.

Warrior

With a monolithic hollopoint you can have it almost both ways. The bullet is areodynamic in flight with a reasonable ballistic coefficient.



243 v.458


155gn 0.375 @ 3300ft/s

Once it hits the target the terminal ballistics creates a shoulder stabilised FN solid. How cool is that?



Mark

Here is the crew that shot the Hippo that I referred to:



Warrior

Warrior

Conventional wisdom and experience is still in favour of lead/copper but the monolithics are proving very successful in the field.
All monolithic (copper/bronze) bullets are going to be light for caliber whatever as the rules were based on copper/lead. The mushrooming on a std roundnose lead/copper bullet does not help stability and usually causes then to deflect of a straight path as they rarely mushroom uniformly. The copper fragmetns are quite large and act as seconary projectiles especaially in a lung shot beast. but in the end the main bullet will penetrate deeper and straighter than the lead copper eqivalent. Basically they work differently and Cape buff have been killed cleanly and effecively with the 155 gn copper bullets shown.

My calculations from field data is that a monolithic FN can have a SD of 0.2 and be equally effective as a lead copper of 0.3.

Regards

Mark

Premium-grade Softs are much more reliable than conventional Softs that are prone to fragment or to lose a lot of their weight. I am using premium softs most of the time and I have had only straight-line penetration from them - perhaps I have just been lucky. Obviously if one encounters heavy bone at an oblique angle deflection is a possibility even with Solids. Whilst a 155 gr Solid bullet can certainly kill a critter like a buffalo, given good shot placement, I would feel uncomfortable if it is to lose another 20 odd percent of its weight and it encounters the thick bones that obscure the heart of a buffalo. The flat cylinder Solid would make a very small hole through the vitals and that is why most PH's have changed over to CEB's (controlled expansion bullets) to make a bigger hole.

I have also done various tests with different bullets in wetpacks and these bullets go straight. Premium Softs that are commonly available in the States, like Swift A-Frame, TBBC, NF gained an enviable reputation over the years with hunters. I tested CDP's, Swift A-Frames, Lapua Mega, Stewart, Rhino's, Claw's, Nosler Partitions, PMP Pro-Amm, Privi Grom, Woodleighs and a buch of conventional bullets. Here is an array of premium-grade Softs that all travelled straight, all coming out of the same wetpack, shot a a few inches apart that travelled straight without veering to one side or cutting into the other bullet's track.



Warrior