Can we revisit the 308 vs. the 3-06 one more time? I swear it is a good question

Q-Man, I think you're on to something! Certain proportions of length and width are more pleasing to one person's eyes than to another's.

To me, the '06 is just "right". The .308 ain't; but the .243 is. Go figure.

Same for rifles, themselves. I'm turned off by "fat" rifles, looking at the depth of the receiver--so I give up a round of magazine capacity. I like the appearance of the Win. 94 over the Marlin 336, although I think the Marlin is a better-engineered gun--particularly if, like me, you need to use a scope.

Purely from a basically-deer-hunting standpoint, where it mostly doesn't matter which rifle you buy, nor which cartridge you use, personal aesthetics is a big piece of the decision.

:), Art

"Welcome to the thread that won't die!"
 
Ok guys I tell you what. I can see this is never going to be resolved. I had a few conversations with a physicist about this and while he did say he was no ballistics expert he agreed that the cartridge shape should have no affect on the consistency of the explosion (i.e. no variation = accurate round). I will make one more attempt to explain. I have enjoyed this conversation a bunch by the way. The concept of variations in how the powder “pushes” on the bullet is negated because of the tightly fitted barrel. Your comments in concept are correct but in practice the bullet cannot wobble around its axis because it is confined to only one possible range of motion within the barrel. It can spiral evenly around its axis. IF the barrel is correctly lined up with the action/chamber/etc it will rotate in an even manner. In the instant the bullet leaves the barrel if the gasses push against one part of the bullet more than the other (as you are claiming) then you would be correct in saying the bullet would begin to yaw. However as others have mentioned that is the purpose of the crown in the barrel. Also as a further item as the bullet travels down the barrel if there happens to be greater pressure at say the top of the bullet, over the course of travel (a near instantaneous correction) these pressures will equalize. This is not even mentioning anything about why a longer case will not have any variations (or pressure differentiations from the center point of the bullet).

Think about the idea of a “caseless” cartridge. Imagine a “tube” if you will of powder with a bullet stuck on top. Now imagine one tube is a certain length and another is half an inch longer. Now using those as your rounds explain how the shorter one will be more consistent than the longer one. Adding the brass does not change a thing. When a round is fired the brass expands (this is why brass is used) to fill the chamber, very closely replicating a “caseless” round.

Also let me again state that while you might be correct to say one case of equivalent accuracy between a 308 and 30-06 is not sufficient, as one rifle here or there might be able to toss the bullet down range just as accurate as another, neither is presentation of 1960’s match contests show much of anything. As I said I can think of plenty of good reasons why this could be due to other causes, not some difference in cartridge design. I am not saying that this is the case, but if a 308 is really more accurate than a 30-06 there should be a TON of modern data to support it.
 
Cheapo, can you show me where to find those test results you mention?

Aggie jokes?! Oh come on! No need to go there. Sounds like "sour grapes" to me. ;)
 
ahenry:

You've missed some of the points. The yaw is induced before the bullet engages the rifling in the bore. The bullet must first jump a short gap ("freebore") before it enters the bore. For high pressure rounds like some of the Weatherby's this can be a considerable gap (as much as .375" in some rifles).

It's the same situation for a misaligned bullet in a case, poor alignment induces a yaw upon firing - that's a well known phenomenon.

With a caseless round, none of my previous argument changes. The combustion chamber shape simply functions as the case/chamber as with a conventional cartridge.

Glad to see that you are also discussing this with "real" scientists. Your physicist friend is simply wrong about the case shape not influencing the "explosion" (powder burns though - it doesn't really explode). If shape has no effect on an "explosion" then why bother with shaped demo charges ? Isn't that's how explosive AP rounds work ? Shape makes a huge difference.

-ric
 
We seem to keep bouncing back and forth between "inside the gun" and "outside the gun". For those interested in "outside", I commend the URL, http://www.povn.com/~4n6/index.htm for your edification.

It is common that bullets yaw for some distance after leaving the barrel before stabilizing. .308/.30-'06 is not part of THAT equation. :) IIRC, the Big .50 folks have looked into this more than others.

Later, Art

"There are only two Aggie jokes. The rest are true stories." (signed) Teasipper.
 
Ric, I am going to assume that your comment about the “real” scientist wasn’t meant as a derogatory one. It was my dad that I was talking about. As long as I have no idea what your scientific background is I will refrain from making comments that question your ability to opine even though I would tend to think that you are more of an armchair scientist like myself. I will refrain from listing the many accomplishments that my dad has had in the arena of science and will just leave it at this, he is plenty qualified to have this statement made about him:
(while) he was no ballistics expert he agreed that the cartridge shape should have no affect on the consistency of the explosion (i.e. no variation = accurate round).
Click to expand...
Be careful what you say...

Let me one more time try to explain what I have said before. Consistency=accuracy. On this we have agreed.
With that as a base point the question of whether or not one cartridge design or another is more accurate (all other things being equal) revolves around the ability of one case to be more consistent in the explosion (yes it is an explosion: the pressures generated in such a short time period, i.e. explosion, is what pushes the bullet) from one firing to the next. I assume that we also agree on this concept.

Your comment on yawing I will confess is a bit out of my realm of knowledge. That being said I hold to my comment on a logical basis. I will try to do some research on this topic and see what I can come up with since I am not going to make claims that can’t be supported.... :)

Now to discuss the caseless cartridge and shaped charges concept. Again I am no demolition expert but I will venture a view here. I agree with you that shaped charges have most of their force working in one direction, but how does that make a bit of difference. Remember that we are looking for one caliber to be more CONSISTENT than the other. Discussing shaped charges merely allows for the possibility that we are directing the force in one direction over and over. I still stand to the concept that the EXACT same shape with the EXACT same load and the EXACT same bullet and the EXACT same barrel and the EXACT same etc... will have the same consistency as any other cartridge design with the EXACT same criteria from round to round. In order for variations to develop there has to be some other force enacted on the bullet prior to its leaving the barrel. Where are those forces? Suppose you have two iron plates with a hole in the middle of them (different sized holes). Now take a hose and blow air onto the plate. If the plate has all out side influences removed and the force of the air is the same then yes the amount of air that makes it through will be different for the different holes but it will be exactly the same for a particular hole every time you blow a consistent air flow through it. I know this is overly simplified but it does illustrate my point.


Art that link looks really interesting. I am going to take a nice long look at it as soon as I can. Thanks for posting it.
 
ahenry:

The "real" scientist comment was meant as a compliment, different opinions - especially informed ones - can only help discussion.

You are right in that I got off track regarding the consistency argument when we began to discuss shaped charges.

Since we are trying to be technically correct remember that gunpowder burns in much the same way a rocket motor burns, it does not explode. The burning of a solid fuel rocket motor and the exploding of a rocket motor are different types of events with dramatically different consequences.

Think about the events that occur as a primer ignites, throwing a cone of hot gases into the powder column. As the powder begins to burn, gas molecules near the case are slowed by friction with the case walls. These in turn slow other gas molecules, others collide with the shoulder then funnel out to the bullet base - the result is that the pressure on the bullet base is not uniform. Although it all happens rapidly it is not instantaneous nor is it an explosion.

Powder packing and case shape affect the pressure distribution. One characteristic of the case shape is the consistency of the pressure (force) distribution across the bullet base.

In your original post you asked for evidence for better accurancy for the .308 over .30'06. You've been provided a good bit of evidence and a basis for such a difference. Your response boils down to 'I don't buy it' but your counter-arguments reveal an incomplete understanding of some of the fundamentals of internal ballistics.

The logical conclusion to your arguemts must be that all case shapes in all calibers are capable of identical accurancy, that is, case is irrelevent to accurancy. On this point i do not agree.

I've enjoyed this discussion, but we are clearly at an impasse.

-ric
 
Ric, thanks for saying you meant the scientist comment as a complement. This written media can sometimes make intended meanings difficult to ascertain. Sorry about my overreaction there. *Doh*

You are correct I have asked for actual evidence that the 308 is more accurate than the 30-06. The only valid submission so far has been the personal experience (quite extensive I might add) of Art. I commented on that as well as thanking him for providing it.
Let me explain why I don’t find the “evidence” presented so far to be conclusive. There was ONE article by a guy that was posted by two different people. The extent of the proof this gentleman provided was matches that took place in the 60’s. I already explained why I don’t buy that out of hand (I think it is a pretty good reason). I am not saying it isn’t true it might be. Then there was a test that was also mentioned that I asked for information to the actual results. This seemed like this might have been the actual test results we wanted to find, but I was never told where I could verify these results for myself. I just think that there should be more believable compilations of data if the 308 really is the more accurate round. Further the explanations given as to WHY the 308 is more accurate make no sense. Sorry to be blunt but your explanation strikes me as the one with an incomplete understanding of basic laws of physics. Exactly replicated explosions (or to make you happy, really fast burning powder) are going to have exactly the same result. In order for there to be a difference there has to be some sort of a force acting on the powder differently from one shot to the next.

The logical conclusion to your arguemts must be that all case shapes in all calibers are capable of identical accurancy, that is, case is irrelevent to accurancy. On this point i do not agree.
Click to expand...
Of course not! Obviously if you try shooting a 22 at a thousand yards you aren’t going to get much in the way of results. That is not what I have been saying. I am saying that given two rounds with the same bullets, and one round moving its bullet faster than the other I can’t find a reasonable explanation as to why the slower one is “supposedly” more accurate. You offered an explanation that didn’t make a whole lot of sense, but given there very real possibility that I don’t know what I am talking about I went and asked somebody that was plenty qualified to opine on the physics of a bullet firing. I offered his view.
I agree that we seem to be at a bit of an impasse that is why I stated several post back that the only real way to solve this is by testing the two rounds in the same type of rifle.
 
Possible experiment ?

I wonder if this experiment would be possible:

1. get two "match-grade" powders
2. get one that takes up lots of volume (ie: is slower-burning)
3. get one that takes up less volume
4. build some super-consistent hand loads using both.
5. Shoot both out of the same rifle, same conditions, etc, and see if the higher volume powder is more consistent.

Ideally, the cases could be loaded with the slower-burning powder such that they are nearly totally filled.

Of course there are many other things to make sure you account for, but this might be one way to avoid the "can't compare different guns" problem and yet test the powder density packing hypothesis.

-z
 
ahenry,

Your analogy of the two caseless tubes, one shorter than the other don't, I believe, quite wash all things considered.

One is still shorter & fatter than the other, which does seem to produce more uniformity. If you were to increase the diameter of your larger (length) tube & then shorten so you maintained that "magic blend" of length to diameter ratio, I'd suspect you'd then be in the ballpark.

There does seem to be a "better" ratio of length versus diameter & perhaps, as with the .300 mag, once you go past a certain point, things change. Too, sharper shoulder angle does appear to have a possitive effect on accuracy but doesn't come into play re .308 vs .30-06.

Beats me. I'm no ballistics expert either inside or out, but it does appear some certain shapes work better than others.

One thing just came to mind .... .22s experience a "strange thing" right at the speed of sound. Sub-sonics are mainly used for high level accuracy because they're not doing the super-sonic then drop down below causing ballistic shift through "the barrier."

Possibility that (other than the already established fact that a .308 is much superior ;) that's a joke) the .308s are travelling at an optimum velocity? .30-06 is in that "difficult stage" & the .300 is past it & back into an optimum groove .... ? helifino
 
Test results are at:

Ahenry, get a hold of back issues of The American Rifleman, 1959 through about 1968. Usually it's the issue right after Camp Perry--September for most years. The article will usually be titled something like "1963 National Match Ammunition" or something like that. About a page of text and a couple of graphs, plus (usually) a windage diagram.

Accuracy is measured with the mean radius method. THAT, I guess, could be another thread entirely. Extreme spread of shots is typically 3 times the mean radius value.

Remember, WE WENT TO THE MOON ON 1960s TECHNOLOGY.

I see no valid reason to discount these test results, as far as the 173-gr FMJBT bullet goes. I also see little reason to doubt that some level of accuracy difference may also be present between the calibers for other bullets.
 
Target showing .308 Accuracy

I have a picture of a target that I shot with a Savage M10 Tactical .308. It's not a target grade rifle. I shoot out of the original barrel that came with the rifle, and the groups that I shoot out of it are phenomenal. I would like to post the picture, but I don't know how. If anyone could tell me how, I would appreciate it. Anyway, the group size is .122" center to center. The rounds are handloaded. I still love the -06 though. It was the first high powered rifle I ever owned. It was pretty accurate too. I usually shot about a quarter sized group on average.

Branden
 
This thread argues for the 300 WSM

Numerous arguments and evidence for shorter, fatter cases with sharper shoulders which explains why the 308 is more accurate that the 30-06 for moderate bullet weights - all this seems to be what the 300 WSM was designed to take advantage of for heavier bullet weights.

Personally, I'm not only in quest of tight groups at several hundred yards but also effective knockdown energy at those ranges. Accurate punching of holes in paper could be done with a Sierra 107 grain 243 (which is a necked down 308). But knocking down elk or dangerous critters at several hundred yards requires more oomph than a paper target. Ergo, I prefer '06 bullets over 200 grains which then require more powder and case capacity. Nevertheless, the arguments for shorter fatter cases and more consistent ignition and burn are quite compelling. The 300 WSM seems to fill that bill.

Any thoughts?

I note that there have been a few 300 WSM discussion threads now which have begun to address this new case on the block.
 
If you want statistics, the best place I can think of would be the military service. For example, Hatcher's Notebook chronicled (among other things) Gen. Hatcher's tests of the national match ammunition over the 20s, 30s, and 40s. They fired it thru static rifles where they could take out all the human error possible, even so, some lots were more accurate than others. Of course, the ammo tested was 30'06 since Hatcher stopped writing about 1947, but it is statistically valid for the data he had. Now, the question is: Who is the Julian Hatcher of today who tests the 308 National Match ammo?:confused:
 
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