Ballistics/hunting question

[Cal]

Originally Posted by Okotokian

So why does anyone ever purchase anything larger than a .243? Are you saying that a .300WM offers no advantages over a small calibre rifle like a .243 within ranges of a few hundred yards, regardless of situation, game (North American game anyway), shot angle, etc.?

You realy are bored here arent you? Coming from a guy who's hunted a few years, and spent as much time on the board as you have, this thread is borderline trolling. I'm pretty sure I've seen you give your .02 on threads very similar to this, as well I'm pretty sure you arent in a line of work where you experience spring breakup, so I'm having a hard time understanding your motives for playing dumb like this.

[Speckle55]

Personal i would go with the 180 grain for your Elk at 400 yards but here is a read/quote

David




Why are there so many bullet weights for most cartridges? In .308 Win. you find bullets from 100 grains to 220 grains. Even the .224 Wthby. Mag. offers 32- to 80-grain bullets. Why?

The old rule of thumb: Use the lightest slugs for varmints (small critters) and heaviest for really big stuff. The basic reality was that heavier slugs retained more weight, thus offered more penetration. Today, things are more complicated. (Isn’t everything?)

No longer limited to standard cup-and-core bullets (soft lead core swaged into thin gilding metal jackets), we can find hard, controlled-expansion, deep-penetrating bullets in amazingly light weights. Monolithic all-copper or gilding-metal bullets such as the Barnes TTSX, Winchester Power Core 95/5, Nolser E-Tip and Hornady GMX retain so much mass after impact that they penetrate as deeply as old, considerably heavier cup-and-cores. Thick-jacketed, bonded-core and/or mechanically locked bullets such as Nosler Partition, Swift A-Frame and Winchester XP3 do much the same thing.

This means we can now choose lighter bullets to accomplish what the heaviest used to do. In the .270 Win., use a 130-grain monolithic bullet to penetrate as deep as (or deeper than) a traditional 150-grain. The right monolithic 130-grain .308 Win. projectile might penetrate deeper than a cup-and-core 180-grain in the same caliber.

But there are other advantages (and disadvantages) to lighter bullets. Given the same basic shape as heavier ones, they almost always fly flatter because they can be started faster. The heavies retain more energy farther downrange, but if you want minimal drop, shoot pointy light ones. Lighter slugs generate less recoil, too, so if you’re recoil-sensitive, light bullets are your friend. Just make sure they’re tough enough to stand up to impact velocities.

Another reason controlled-expansion (monolithic) bullets penetrate better than their weight suggests is because they don’t expand as much as soft lead. Mushrooming is good for increased wound area, bad for penetration. The flatter the bullet deforms on impact, the more it drags. A great compromise for penetration and radial tissue damage is expansion of 1.5 to 2X original diameter. Combine that with virtually no loss of mass and you’ve got the best of both worlds.

A final factor in choosing bullet weight involves wind drift. The heaviest slugs (of any given materials) are always the longest, and, given similar nose and tail shapes (long and sleek,) they have the highest ballistic coefficients (B.C.). This means they resist air drag, retain more energy downrange and deflect the least in wind. So while they’ll fall faster than lighter slugs, they’ll deflect less in the wind.

Regarding my feeling about bullet weights in the face of wind drift, consider this scenario: Out West, coyotes are often hunted in strong winds, so minimizing wind deflection is smart. Gravity is constant, so once you know your bullet’s speed and B.C., you can chart its drops and calibrate your scope sighting system to handle that. But judging wind is as much art as science. I try to minimize wind deflection by using the heaviest, highest B.C. bullet I can in my long-range coyote rifles. This means I probably shoot a 75-grain Hornady A-Max or Swift Scirocco in my .22-250 Ackley. At 3,350 fps, both drop a lot more at 400 yards than my 55-grain Nosler Ballistic Tips or Sierra BlitzKings at 3,800 fps, but they deflect much less in the wind. Because I can’t predict or even accurately measure wind speed, I increase my chance for hits with the heavy bullets over the light.


Light bullets shoot flatter than heavy bullets of the same caliber, but the high
B.C. of heavy projectiles ensures they retain more energy downrange and drift
least in wind. A stout, controlled-expansion light bullet can penetrate as well as
a much heavier one of softer construction. (Pictured: .264 Wthby. Mag. bullets.)

[winmag]

Big and or big dangerous game minimum 30 caliber no doubt there. The best heads [ for me partitions]load for accuracy and extreme speed in case you have to line bore a charging bear or snap a shot at a moose in the swamp and a neck shot turns into a Texas heart shot or a elk facing you so you can take out the rear hip or a buffalo neck and shoulder shot you need bone crushing energy and most of the older hunters here have been in that predicament i am sure . You hunt hard all week and when a close opportunity pops up you take it,smaller calibers for the most part are for broad sides. My wife had a 270 and moose died where they stood with neck shots same as deer with my 243 but i still like my meat in the pot 30 caliber.

[elkhunter11]

Big and or big dangerous game minimum 30 caliber no doubt there. The best heads [ for me partitions]load for accuracy and extreme speed in case you have to line bore a charging bear or snap a shot at a moose in the swamp and a neck shot turns into a Texas heart shot or a elk facing you so you can take out the rear hip or a buffalo neck and shoulder shot you need bone crushing energy and most of the older hunters here have been in that predicament i am sure . You hunt hard all week and when a close opportunity pops up you take it,smaller calibers for the most part are for broad sides. My wife had a 270 and moose died where they stood with neck shots same as deer with my 243 but i still like my meat in the pot 30 caliber.

And there isn't a single species in Alberta, that I wouldn't be comfortable hunting with my 7mmSTW. The new monometal bullets in .284", will penetrate just as deep, or deeper, and will break as much or more bone than your 30 caliber Partition will. Bullet construction, is far more important than bullet diameter.

[winmag]

agreed Elkhunter11 but that's like having a 270 plus on steroids and yes bullet type is key in faster bullets , i have used the 180 Spitzer Partition for 30 years have enough supplies for twenty more if i make it and my knees hold out ,don't reload much , sold most of the hardware except a few keepers. Kinda getting back into waterfowl again. The later post was actual observations but it still gets down to basic bullet placement and shooting discipline , a broadside double lung shot even with a 22 short will be lethal winmag

[marxman]

Oki you know the meaning of bullet diameter, weight, and their rational product, s.d.. These numbers are honorable stats but subversives busy in any thread that brings up this subject will throw red herrings around so dont encourage them unless of course you are doing it on purpose

[elkhunter11]

Oki you know the meaning of bullet diameter, weight, and their rational product, s.d.. These numbers are honorable stats but subversives busy in any thread that brings up this subject will throw red herrings around so dont encourage them unless of course you are doing it on purpose

The simple fact is that the only sectional density that matters at all, is the sectional density as the bullet passes through tissue. This changes considerably as the bullet expands and sheds weight. As such, the sectional density of the unfired bullet is pretty much meaningless, unless the bullet never expands, or sheds any weight.

[marxman]

Originally Posted by elkhunter11

The simple fact is that the only sectional density that matters at all, is the sectional density as the bullet passes through tissue. This changes considerably as the bullet expands and sheds weight. As such, the sectional density of the unfired bullet is pretty much meaningless, unless the bullet never expands, or sheds any weight.

according to the hornady site "ballistic co efficient calculations involve both shape and sectional density factors" so sd matters on the way to the target and if you cut the sd of one of your 7 mm bullets in half you would not be happy with the results. the amount of energy it arrives with for a certain diameter is dependent on sd and speed. the bullet could not expand and shed weight without the sectional density it arrived with to drive it. of course the sectional density of an unfired bullet is meaningless but as drag acts upon it whether from the air or the target sectional density matters all the way. i would have to say your post doesnt make sense and in fact, its nonsense

[elkhunter11]

according to the hornady site "ballistic co efficient calculations involve both shape and sectional density factors" so sd matters on the way to the target and if you cut the sd of one of your 7 mm bullets in half you would not be happy with the results.

So to calculate the ballistic co-efficient of a bullet, you need to know the sectional density of the bullet? Looking at the equation for calculating the ballistic co-efficient below, where do you input the sectional density?

http://www.jbmballistics.com/cgi-bin/jbmbcv-5.1.cgi

Using the calculation below, try changing the bullet diameter, or the bullet weight, either of which changes the sectional density. Does it change the trajectory? Given that you don't need to know the Sectional density to calculate the B.C. or the Trajectory, the Sectional density of the unfired bullet, can't be that important.

http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

[Jordan Smith]

Sectional density is a direct factor in the equation to calculate B.C...

[marxman]

i looked at your site elk it involves back calculation of bc by chronograph performance observations you cannot calculate bc from the physical properties of the bullet alone without sd whether its in the calc as sd or as mass over diameter times a constant its the same thing. there are different versions of the equation

[elkhunter11]

i looked at your site elk it involves back calculation of bc by chronograph performance observations

Which leads to to the actual B.C. rather than a theoretical B.C.. Theoretical B.C.s published in manuals, or in manufacturer's data, have been shown to be in error, which has resulted in some manufacturers releasing new B.C.s for their bullets. On the other hand B.C.s derived from actual shooting, are much more reliable.

Knowing the Sectional density of a bullet really has no practical value, in that calculating the actual B.C. by shooting is more accurate than any theoretical calculation, and you can't accurately predict performance on game of a bullet from the sectional density.

Those people that think that sectional density is so important, can keep on quoting their theories, based on sectional density, but I will keep on believing what I see by actually shooting bullets, at targets, and at game animals. Seeing the actual trajectory of a load is far more credible than any calculation can ever be, and examining wound channels, in game animals, is far more informative than any theory , based on any calculation, will ever be.

[marxman]

of course a result derived from actual performance will be more accurate but it is still the product of the physical properties of the bullet none more important than sd! in ohms law you only have to know 2 factors to predict the third, should we say the third is not an inextricable part of the relationship because we dont know its value? you have a lot of twists and turns to get away from the truth

[elkhunter11]

of course a result derived from actual performance will be more accurate but it is still the product of the physical properties of the bullet none more important than sd! in ohms law you only have to know 2 factors to predict the third, should we say the third is not an inextricable part of the relationship because we dont know its value? you have a lot of twists and turns to get away from the truth

The point is that some people still insist that they can predict the performance of a bullet on game, by looking at the sectional density of that bullet. The simple truth is while sectional density may have been somewhat useful for that purpose in the days of all lead bullets, or with the simplest of cup and core bullets, that isn't the case today. These days, the construction of the bullet, the impact velocity, and the bullet placement, are the factors that matter far more than any other factors, where bullet performance on game is concerned. The performance on game can't be calculated, simply by using numbers. As far as trajectory is concerned, only the B.C. of the bullet, and the velocity matter.

[Jordan Smith]

When talking about terminal performance, SD has become an outdated standard of measurement in regards to how a bullet will perform on game. It certainly still has an influence here, since a 200gr Partition will penetrate deeper than a 150gr PT, but it's not nearly as important as it used to be when comparing one C&C bullet against another.

If talking about external ballistics, however, then SD is important. The BC of a bullet is a direct result of its SD and its form factor. It's that simple. The form factor may not be easily calculated, which is why actual shooting gives more accurate BC numbers than estimating the form factor and calculating a BC, but the SD does matter. That is why a bullet made entirely of copper has a lower BC than an identically shaped bullet made of lead. It weighs less. It has an identical form factor, but it carries less momentum as it pushes its way through the air. This is a law of physics that we must recognize.

But all things considered, I completely see what you're saying elkhunter- too many people put WAY too much emphasis on the SD of a bullet, judging its terminal performance entirely based off of that one number. There are a host of other things that are higher priority on the list of factors involved in how a bullet performs when it meets flesh and bone.

[elkhunter11]

That is why a bullet made entirely of copper has a lower BC than an identically shaped bullet made of lead. It weighs less. It has an identical form factor, but it carries less momentum as it pushes its way through the air. This is a law of physics that we must recognize.

It is true, that an all copper bullet, made in the identical shape of a lead core bullet will have a lower B.C., but that all copper bullet will also be lighter, so it can be driven faster using the same chamber pressure. That extra velocity does make up for some of the losses do to a lower B.C.

As well, the bullet manufacturers are working to make monometal bullets with similar B.C.s to the common cup and core bullets, of similar weight. The 7mm-139gr GMX lists a very slightly higher B.C. than the 7mm-140gr Accubond. The 7mm-145gr LRX is five grains heavier, but it also offers a very slightly higher B.C. than the Accubond.

But all things considered, I completely see what you're saying elkhunter- too many people put WAY too much emphasis on the SD of a bullet, judging its terminal performance entirely based off of that one number. There are a host of other things that are higher priority on the list of factors involved in how a bullet performs when it meets flesh and bone.

My point all along, yet some people fail to recognize this fact.

[Dumbo_Dave]

Originally Posted by Cal

"Killing power" is a pretty obscure term IMO because animals of different sizes require completely different bullet performance to provide quick kills. Bullet performance is what makes for good "killing power", more so than caliber or bullet weight. As well a bullet that makes lightning kills on animals such as deer is quite often far from ideal for killing moose and vice versa. To further complicate things bullets often perform differently in different chamberings. For instance I'd shoot a moose with a 165 grain coreloct bullet out of my 30-06 win with confidence and without a second thought, from a .300 wby I would not use that same bullet for such a task.

The statement "bigger is better for killing power" is such a broad statement that I cant help but argue that without further definition of the peramiters for comparison the statement is false.

If that were true, a 50 BMG wouldn't have much of an advantage over a .17 in killing Elk or big Bear. We all know that is ludicrous. When you move those parameters to something less extreme, you can argue all day without proving anything. Myself, If i ever go for dangerous game, I want the biggest baddest bullet that I can handle - even considering the 50.

[Okotokian]

Originally Posted by Cal

You realy are bored here arent you? Coming from a guy who's hunted a few years, and spent as much time on the board as you have, this thread is borderline trolling. I'm pretty sure I've seen you give your .02 on threads very similar to this, as well I'm pretty sure you arent in a line of work where you experience spring breakup, so I'm having a hard time understanding your motives for playing dumb like this.

Thanks for the input/sarcasm.

But I'm really trying to understand this. I get that it's about shot placement, to a degree. But when you hit bone, etc. I was trying to figure out whether smaller and faster or slower and larger would be better. It's really a question of where the speed vs weight/size axes cross. Are there any situations where one caliber would be favoured over another? In a nutshell I'm trying to decide whether I should get a 30-06 or a 270wsm. See, bigger/slower vs smaller/faster. Real decision to make, honest questions. Not trying to argue with anyone, trying to understand.

So if you don't like the questions how's about you just don't open this thread and keep your thoughts and indignation to yourself, OK? We'll all be happy then, right?

[Okotokian]

Originally Posted by marxman

i looked at your site elk it involves back calculation of bc by chronograph performance observations you cannot calculate bc from the physical properties of the bullet alone without sd whether its in the calc as sd or as mass over diameter times a constant its the same thing. there are different versions of the equation

LOL OK, this discussion is WAY beyond me now. I dropped high school physics. But I think I've gotten about as much as I can from this discussion. There is no written in stone answer for me but some interesting points to ponder. Thanks guys.

[Jordan Smith]

Breaking through barriers like bone is about bullet integrity and momentum. Try shooting some Barnes TTSX bullets at something like a deer hide in front of a 1" block of concrete with a block of ballistic gel behind, and you'll see a very real comparison of a lighter .270 TTSX vs. a heavier .308 TTSX.

[elkhunter11]

Breaking through barriers like bone is about bullet integrity and momentum. Try shooting some Barnes TTSX bullets at something like a deer hide in front of a 1" block of concrete with a block of ballistic gel behind, and you'll see a very real comparison of a lighter .270 TTSX vs. a heavier .308 TTSX.

And if game animals had a shell made of concrete, such a test would have some validity where shooting game animals is concerned. My 7mmstw rifles have driven the 140grTTSX through the larger bones of an elk, with very good results.

[Jordan Smith]

Same old rhetoric. I'm not sure why you're criticizing my theoretical example- I'm arguing the same thing as you are!

My point is that bones are hard barriers very much like concrete, and very much unlike lung tissue and other soft tissues. Getting a bullet to break through a barrier like that is different than asking the bullet to penetrate long distances through soft flesh.

Of course concrete is not the same as bone, but it serves to illustrate the principle of barrier penetration. What I'm suggesting is that you'll find that the results from the .270 and .308 differ minimally. Some of the deepest penetration I've seen, as well as in many penetration tests I've read, are with the 100gr TSX bullet. Even when compared to .308 versions of same.

I've also driven the 140gr TTSX from my 7WSM diagonally through the scapula of a bull moose, leaving a 5" wound channel through the vitals and a 3" exit hole through the ribs. That bullet went through 48"+ of moose before exiting.

Penetration through barriers is MUCH more a function of bullet integrity and momentum than bullet diameter.

[elkhunter11]

Of course concrete is not the same as bone, but it serves to illustrate the principle of barrier penetration. What I'm suggesting is that you'll find that the results from the .270 and .308 differ minimally. Some of the deepest penetration I've seen, as well as in many penetration tests I've read, are with the 100gr TSX bullet. Even when compared to .308 versions of same.

From what I have witnessed in the field, I have to agree, with the monometal bullets, unless you go to the extremes, caliber and even bullet weight don't seem to all that much of a factor in on game performance. The only thing that I have really noticed with the monometal bullets, is that they perform best at higher impact velocities.