[thumbtack]

Today on Gun Talk Tom Gresham said that the .308 was more accurate then the 30.06. Can someone explain how and why?

I compared the muzzle velocity between the two(same bullet and powder) in my reloading manual and the 30.06 almost always had a high muzzle velocity. I would think that it would shot flatter longer with a higher velocity.

If it true that the 308 is more accurate then what am I overlooking?

[seeker_two]

This is one of those times I'll have to respectfully disagree w/ Mr. Gresham...

In comparable rifles firing loads that are accurate to THAT RIFLE (every firearm is a law unto itself), the .30-06 & the .308 are equally accurate. The same can be said of the .270, the 7mm-08, the 7x57, and any other caliber. It's the individual rifle--and the individual shooter--that makes the difference.

The only significant difference b/t the two is that the .308 uses a shorter action. That makes little difference in accuracy, but can be a difference in second-shot speed.

Hope this helps...:D

[Tom C.]

In an absolute sence, the .308 has a slight advantage in target rifles. The smaller case capacity makes it a little more uniform. In a sporting rifle, it would be statistically impossible to tell any accuracy difference.

[BHP9]

Tom C is right and I might also add something. When a man by the name of Pindell along with his partner whose name escapes me at the moment studied cartridged shapes as related to accuracy they found not one but two factors that convinced them that the shorter cartridge was the more inherently accurate one.

Besides what Tom C already mentioned in regards to burning uniformity of the powder there is a phenominon called "out of square bases".

I probably will not do a very good job of explaining this because it has been some years since I read about it so if anyone who knows about his would like to add to what I am about to say please feel free to do so. But here goes.

If you ever took a look at the leaning tower of Pizza you will see that the tower leans quite a bit. Now if you put a cartridge case on a dead flat surface such as a piece of glass and you have a measuring device you will see that very few if any of them stand perfectly straight. They actually all lean to some degree because of out of square bases. Pindell found that the shorter cartridge even though it may start out with the same lean as the longer cartridge it has less run out when measured. When the longer cartridge is put into a rifle's chamber it is way more out of alignment with the bore than the shorter cartridge is.

This discovery enabled Pinell to come up with two of the most accurate target cartridges in the world," the .22 PPC and the later 6mm PPC". This started a new evolution in the design of more modern cartridges and even recently I believe Winchester has now just brought out a new .22 centerfire that has about the same ballistics as the 22-250 but is much shorter and fatter. People are asking "why invent this cartridge". It was done because of the pursuit of the ultimate accuracy in varmint rifles. The shorter cartridges have proved that when averages are taken they do shoot better but here again the difference is never noticed by the average Joe with the average factory production rifle. You actually have to get into precision made heavy duty bench rest Actions before you would see the very slight difference in the average overall accuracy. Of course the Factories are not going to tell you any of this because they are out to sell production grade rifles based on actions originally designed for sporting rifles and military rifles. You actually have to get into the massive and heavy bench rest actions before you will really start to see the difference in the higher scores you will obtain.

[twoblink]

Also, the 308 from what I read was the first round to be computer assisted in its design.. The necking angle gives it a more uniform burn internally and a more consistant push (pressure wise) you can see this evidenced by the .357Sig vs. say the .40SW. You can crank it so that the bullet weight of both and the powder charge is the same, but the 357Sig will be a bit more accurate because it's more consistant..

Tom was correct... if he added the words (for the most part) or (in general)..

This is the general rule, but of course, there are exceptions..

[gk1]

I believe that the other "P" in PPC was Palmisano (not sure on the spelling, but it's close).

Short, fat cartridges are superior to long ones from an engineering standpoint, but the differences are insignificant other than on paper for most applications. Of course, that's true of just about every aspect of cartridge selection (i.e., very few rifle/shooter combinations can perform well enough to take advantage of the difference between (for an extreme example) a .308 and a .300 WSM in drop and wind drift).

The difference between .30-06 and .308 is smaller than most, but is calculable by people smarter than I am. Short actions are also stiffer (on paper) than comparable long actions, but again, these differences are so insignificant as to be, well, insignificant.

George

[Art Eatman]

To add a little bit: From everything thrashed out back at TFL, plus some reading of various thoughts about the .308, the case is a bit more efficient from the standpoint of uniformity in the burning of the powder.

Generally, the statistical deviations in chronographing muzzle velocity are smaller for the .308 than for the '06. This would support the "uniformity" idea.

Uniformity is a primary item in the search for accuracy.

The .308 starts to fall behind other cartridges when very long ranges come into the picture. It doesn't do well for muzzle velocity with bullets above 180 grains, and the ballistic coefficent of 200-grain bullets is higher.

Purely opinion on my part, but for long-range targets, something like the .300 WSM should prove to be superior.

Art

[Kimber Kid]

I also heard Tom say the .308 is inherently more accurate. I agree. Faster and flater vs accurate are two different things. The 06 has greater case capacity and using slower powers with heavier bullets (165 gr and up) will edge out the smaller 308. The medium burning rate powders filling the 308 case (even compressed charges) using 125 to 150 grain bullets will have the same velocity as the 06. Actually it will be so close it will depend on the particular rifle. The 308 may have a slight advantage. Two like calibers shooting the same ammo in the same caliber may have different velocities and these velocities will change as the barrel wears. The difference in bullet weights should be represented by the barrel's rate of twist. 1 in 10 for the 06 as compared to 1 in 12 for the lighter, actually shorter bullets of the 308, as it's the OAL of the bullet that determines the twist. But weight and twist go together, usually.

Remember we are talking in the most general kind of terms here. overall. Why is the 308 more inherently accurate. A lot of the reasons are listed above, all very good reasons. But are they the only reasons? I'm not sure. Certainly there appears to be a point of case capacity vs bore that is conducive to accuracy. The 308. 6PPC and 222 Rem demostrate this well and it's hard to deny. They are all "inherently accurate", forgiving and easy to get along with tolerant of several powders, bullet weighs and styles.

We are also being told that case configuration as with the new short magnums can lend itself to more power. A more effecient burn column is one of the reasons. But again is it the only reason?

Sorry to put you guys thru this long post only to find my answer is,...I don't know.

[Mike Irwin]

BH9,

Wasn't Pindell's partner named something like Palmisario? For some reason that sounds familiar...

[Gewehr98]

I'll qualify that by saying there are probably a bunch more .308 rifles that exhibit excellent accuracy than their counterpart .30-06 rifles.

Internal ballistics are a wonderful thing. Uniform combustion is a wonderful thing. Uniform combustion with a quality rifle is an even more wonderful thing.

Take two identical rifles. Let's go balls-out and make them Nesika Bay long actions, with, oh, say, one of Boots Obermeyer's barrels, or a Krieger barrel, both in .308 bore. Keep the tolerances just as tight on either rifle. Chamber one in .308 Winchester, and the other in .30-06 Springfield. Handload premium ammo for both rifles, taking the same care to make a quality, match-grade or benchrest-grade round each time.

See which gun is more accurate. Will there be a difference?

My point is that once a .308" bullet, having been pushed to a certain velocity in a barrel, doesn't really care how it got to that velocity once it leaves the muzzle, either from the .308 Winchester or the .30-06 Springfield. It's leaving a barrel at a given velocity, following a given trajectory, enroute to the target. It doesn't have reach-back capability to it's parent cartridge for mid-course correction. So if the 168gr Sierra MatchKing bullet's being pushed consistently, round after round, by either a 42 grain charge of IMR4895 in a .308 Winchester case, or a 47.5gr charge of IMR4895 in a .30-06 Springfield case, it's gonna fly, from the exterior ballistics standpoint, in an arc that can be adjusted to duplicate the other rifle. And, if all things in the playing field are made level with respect to fit and finish of the launching device, the accuracy differences are going to be down there somewhere in the noise level.

That's not saying a .308 Winchester rifle doesn't have some other accuracy advantages over it's .30-06 counterpart. Short vs. Long actions can be one of those differences. System harmonics can be another. Wish I had the money to build the above hypothetical Nesika Bay rifles.... ;)

[Handy]

98,
The downside to your arguement is that you don't really address the consistancy issue.

Issues like barrel harmonics and bore velocity go hand in hand. If you want the bullet to leave the barrel at the same point in it's oscillation every time, the bullet had to have travelled down the barrel at the same rate, everytime.

Same acceleration curve, same muzzle velocity, EVERY time.

So the bullet does "know" what happened to it on the way out because it affected where the muzzle was pointing when it got there.

What the .308, or any case designed in that way, does is ensure more uniform pressure curves so each shot behaves more similarly, coaxing the barrel into the same position.

It's not lost on anyone that .30-06 is decently accurate. But the handloader has to work harder to achieve the same consistancy because the powder burns less consistently down that longer tube.

[gun-fucious]

so fired in a perfect vacuume
a .308 is going to hit a flea at 100 miles
but the 30-06 is going to only hit the dog?

:neener:

[Tom C.]

Before the .308, the .30-06 was the highpower caliber, in 1903 Springfields and later M-1 Garands. It was more than decently accurate, out to 1000 yds. In the 30's someone won the Wimbledon cup 1000 yd match with a .300 H&H. Was the bigger .300 H&H as accurate as the .30-06 at 100 yds? Probably not, but it was probably pretty close. What it did was handle heavier, lower drag bullets at higher velocity to reduce wind drift at 1000 and make hits easier. The .30-06 is like that with the .308. Very small delta in accuracy, but it does handle heavier bullets better for longer range.
As a sporting round, it handles the same bullets to slightly higher velocity, or one step higher in weight to the same velocity(165 gr. bullet in the '06 to about the same vel as the 150 in the .308).
In picking one, the type and model of rifle you want to use probably has more to do with the final selection than any differences in the cartridges. The average accuracy of the two is close enough that it is really a wash.

[Kimber Kid]

or one step higher in weight to the same velocity(165 gr. bullet in the '06 to about the same vel as the 150 in the .308).

If this is the results you are getting you are doing something wrong. :eek: The 06 will have a hard time keeping up with the 308 when both are using 150 grain bullets, the 308 will yeild a 100 FPS increase over the 06's 165 grain bullet when pushing a 150 grainer, and the 308 will do it more accurately. The 308 shines with the lighter bullets, that's why a 1 in 12 twist should be used. At 180 grains the tables have turned.

Inherent accuracy does exist. It has been considered that pressure on the exiting bullet can hinder accuracy. Sure wind can affect accuracy down range so can a lot of things. The skill of the shooter to read the wind means a lot not to mention pure luck. The 308 has broken the Camp Perry record set by the 06.

[Gewehr98]

If this is the results you are getting you are doing something wrong. The 06 will have a hard time keeping up with the 308 when both are using 150 grain bullets, the 308 will yeild a 100 FPS increase over the 06's 165 grain bullet when pushing a 150 grainer, and the 308 will do it more accurately.

Ok, what reloading data are you using, KimberKid? Just a cursory look at some of my loadbooks, and a few websites like www.reloadammo.com, as well as Steve's Pages, says that the .30-06 can rip those 150gr bullets out over 100fps faster than the .308, which makes sense considering the powder capacity of the larger case. Of course, you can always list a reduced load for the .30-06 and say that the .308 will beat it... :banghead:

Yup, the .308 has broken the Camp Perry record of the .30-06. Does that come as a surprise, when armorers and gunsmiths move on to the chamberings that can be still supported? Just like the .223 Remington is showing up better at Camp Perry as opposed to the .308 Winchester. Nobody wants to put the time and effort into a weapon system that's neither current nor supportable with spare parts and armorer experience.

[Kimber Kid]

Gewehr98, Sir with all respect.

What happens in a shooting tunnel from a test barrel can differ from the real world. In a recent range shoot a bystander asked if I would try his 06 Rem auto thru my chrono. A asked him what ammo he was using and he replied 150 grain. I could see that they were new factory and I fired one thru the traps as he requested. The results were his bullets were traveling almost 300 FPS slower than my 308 handloads. Why?... the short barrel on his carbine was killing his 06. I mention barrel length and other factors than affect velocity in a post above. To expound on this a little, the more efficient a caliber is the less it will suffer from a shorter barrel. It's true the 06 has a bigger case and will hold at least 10 more grains of powder and if one is seeking speed for speeds sake it should be no problem using this much more powder to push the 06's bullet slighty faster than the smaller cased 308. Right?...that's a given. BUT...through out this tread the words "inherent accuracy" has been injected. I know some will argue that it doesn't exist. We have to hit what we are aiming at and not just hit it we are comparing the 06 to the 308. A tall order indeed.

Here are some LAB notes from Speer's Manual #13

"We've had many callers ask why the 308 velocities shown are equal to or better than some of the 30-06 velocities shown a few pages ahead. They ask if it's a mistake. No, it's real, and there are two reasons.

First the compact case and a higher pressure limit give the 308 an edge with bullets up to 150 grains, Things are about equal with the 165 grain bullets, but the big 30-06 case's ability to hold a lot of slow-burning powder gives it the upper hand with heavy bullets.

The second reason is the sporting rifles we used to record final velocities. Both have 22" barrels and were bought at the same time. The 30-06 sporter posted velocities about 50-100 ft/sec behind the 24" pressure barrel. That's normal. On the other hand the 308 was consistently equal to or faster than the pressure barrel. Like we've said several times, all sporters are different! See "Why Ballisticians Get Gray" in the Handgun section." end report
____________________________________________________

Bullets will very very rarely have the same muzzle velocities from the same gun, shot from the same lot of ammo, during the same shooting session. So how can a manual tell you how fast your bullet is traveling that was shot from another gun, months if not years before and thousands of miles away? Furthermore, why is so much consideration given to the caliber of a new rifle without a second thought given to the barrel length? Something to think about when buying that new short barrel mountian rifle or carbine. One can say a 30-06 is 100 FPS faster than the 308 but that is speaking in the same general terms as I am when I say the 308 is the most accurate 30 caliber there is and the difference in velocities with bullets between the weight of 125 grains and 150 grains isn't enough to hang your hat, one way or the other.

[Tom C.]

You are getting into some of the details of ballistics. The .308 has a higher pressure rating. The .30-06 is loaded down by some factories due to the availability of older, questionable guns. There is also the phenomon of "fast" and "slow" barrels, as well as barrel length.

I looked at the tables from IMR and Hodgdon. Tables showed the same thing. With 150 gr. bullets, the .30-06 has a little less than 100 fps advantage over the .308 with optimim loads, with the .308 loaded to slightly higher pressure. With heavier bullets it is about the same, but slower powders are required for the .30-06. If you load 4895 in both, to similar pressures, the velocity is about the same.

What this means is in a Garand, there isn't any difference. You need to load the .30-06 with slower powders than the Garand will tolerate to extract the modest performance advantage.

When you want to look at the PPC type of short, fat powder column, compare the new .300 WSM to the .300 Win. They produce similar velocity with the WSM having less capacity.

[Gewehr98]

PRESSURE

If commercially-loaded domestic 8mm Mauser ammo were loaded to European specs, it would sit right there with the .30-06 in power levels. Due to all the older 88 Mauser rifles in country, Remington, Winchester, and Federal all download their 8mm Mauser ammo to prevent accidents. Same goes for commercial .45-70 loads, they're based on the Springfield Trapdoor action. Pressures are purposely kept low at the behest of the liability lawyers.

I'm sure some enterprising individual has proved that he can load the .308 Winchester to approach .300 Winchester Magnum velocities, using a rifle with a tight chamber, thick brass, and a compressed load. Having a .308 load beat a .30-06 for a given bullet weight is simply a matter of pressures, take it or leave it.

A gas-operated Remington autoloader, especially with a shorter barrel, is gonna suffer in the velocity department, especially when it's up against a bolt gun with a considerably longer barrel.

The .308 Winchester/7.62mm NATO round is an efficient number, there's no mistaking that. It's purpose in life was to duplicate .30-06 ballistics in a package that was easier for the troops to carry. A close ballistic cousin, the .300 Savage, was under consideration for the job before losing out to the Winchester offering. In the right gun, the .300 Savage also posts excellent accuracy results.

I like Handy's reply to my diatribe above. I especially agree with his consistency statement. But I'm also of the opinion that a uniform pressure curve and barrel departure timing for the .30-06 bullet can be achieved without giving up much of anything to the .308 Winchester round. We are, after all, talking about a change in burn time of what, microseconds or milliseconds? That's a matter of adjusting for the harmonics, IMHO. The longer .30-06 based cases still have tricks up their sleeves, even if they don't have the efficiency of their short and squat little cousins. Take a look at the 6.5-06, and it's more recent sibling, the benchrest-darling 6.5-284. ;)

[Art Eatman]

A buddy brought a 20" .308 tack-driver out, and we compared it with my 26" '06 Pet.

I shot both rifles, at 400 yards. (This session is what led to my setting up a 500-yard range.) I was using my old standard 150-grain hunting handload. He had brought some Argentine GI stuff.

Both rifles were zeroed at 200 yards.

I had to hold almost a foot higher, and a foot more windage, with his .308 than with my '06.

Obvious reasons: My longer barrel, and my higher pressures in the handloads.

Based on observed performance at 400 and 500 yards, and interpolation from the Sierra Handbook ballistics tables, I'm getting around 3,100 ft/sec from my setup. I'm sorta dubious that a .308 with a 22" barrel can do this.

But if I wanted a 22" rifle, I'd pick the .308 over the '06. About equal velocity and less weight to tote...

:), Art

[BHP9]

I like Handy's reply to my diatribe above. I especially agree with his consistency statement. But I'm also of the opinion that a uniform pressure curve and barrel departure timing for the .30-06 bullet can be achieved without giving up much of anything to the .308 Winchester round. We are, after all, talking about a change in burn time of what, microseconds or milliseconds? That's a matter of adjusting for the harmonics, IMHO. The longer .30-06 based cases still have tricks up their sleeves, even if they don't have the efficiency of their short and squat little cousins. Take a look at the 6.5-06, and it's more recent sibling, the benchrest-darling 6.5-284.

If this were true then the real pro's who compete at long range matches at Camp Perry would be using the 6.5-06 and the 6mm/284. They are not. But they are using 6.5 wilcat calibers and some of them are becoming the dominate wining calibers for long range competion. Many are short and fat and they are definitely not in the magnum class and or burning large amounts of powder.

In the scheme of things today the long '06 length cartridge is about as obsolete in competition as the Do-do Bird. If it were not so you would still see the Ghost of Warren Page competing at bech rest matches with them and not the current short and fat cartridges like the Remington BR series or the .22 PPC or 6mm PPc.

A gunsmith these days specializing in building target rifles for 30-06 cartridge length rifles would be about as lonely as the Matag repairman and would probably be sitting around drinking coffee with him.

Only a few short years ago people were showing up in across the course competiton that includes 600 yard shooting with the longer and higher velocity 22-250 with fast twist barrel's in bolt guns. Now these same people today are all using sem-auto AR15's in .223 with long heavy bullets at much lower velocity and much longer barrel life. And they win with them.

[Gewehr98]

Sorry to hear the 6.5-06 and 6.5-284 are making a poor showing in the long-range competitions. Better let these 1000-yard folks know that, just in case:

http://www.virginia1000.com/02va_m5.htm

And another match:

http://www.virginia1000.com/02va_m8.htm

North Carolina 1000 yards:

http://www.nc1000ydshooters.com/00_statistics.htm

In Sacramento (my old 1000 yard range):

http://www.sacvalley.org/Rifle/1-NBRSA%20EQUIPMENT%20LIST2002.htm

Glad to see they're at such a disadvantage with those icky chamberings! :scrutiny:


(Cratz2, if you're paying attention, your 6.5-284 factors in here nicely!)