.30-06 vs. .308 Win.: Long Range Choice?

[Bart B.]

I'll resume this thread from the other one that really got off the original topic.

First the reason the .30-06 was dumped years ago as a favorite cartridge for high power competition was because it didn't shoot as accurate as the .308 Win. did. Why was due to two things; one bigger and one smaller. Here's some info that's from the '60's and '70's for you nay sayers to take issue with.

It wasn't the barrels. They were as accurate then as they are now. If they werent, then nobody back then would have been able to shoot several consecutive 10-shot groups at 600 yards all under 1.5 inches and some under 1 inch. One's about 7/10ths inch and pictured in a Lapua bullet ad in a late 1971 American Rifleman. Other similar groups were often made testing their .308's from machine rests. Groups from .30-06 rifles were typically no smaller than 5 inches and a very rare one about 4 inches.

Wasn't the bullets, either. The best 168's and 190's would shoot consistantly in the upper 0's and 1's; one 10-shot group after another and another. Oft times these super accurate ones would be separated from the normal production lots then packaged in 1000-bullet plain boxes and sold at the bigger matches. They didn't have the lanolin sizing lube cleaned off and weren't polished shiny bright.

'Twasn't the cases, either. The best cases for either one from Western Cartridge Company were as uniform as the best ones made today. Even if they werent, case uniformity isn't critical anyway except for case weight and a 2-grain spread is good enough.

'Tain't the wind bucking ability either. Although a given bullet weight could be shot out a .30-06 barrel about 5% faster than a .308 Win., that's about the same improvement in wind bucking ability over the .308's slower ones. It's small enough to be masked by the .308's better accuracy anyway.

The big difference in accuracy between these cartridges was caused by two other things. The lesser one can be fixed by replacing one part in the rifle quite often. If the other can be fixed, or has already been fixed, that's fine by me. Then the venerable '06 would be very close to the .308 for long range accuracy.

Some of you may be able to determine what the causes were. If you know what's critical to long range accuracy, it should be easy to figure out.

Have at it......

 

[MCMXI]

Bart B., I like your thought-provoking posts.

If you know what's critical to long range accuracy

I load for and shoot .223 Rem, .308 Win and .300 Win Mag at 600 yards but I've never owned a .30-06 rifle. However, despite being fairly new to this mid/long range stuff and still going through the process of figuring out what's "critical" to long range accuracy, consistent velocity is definitely up there on the list. BC, bullet drop and wind drift are all functions of velocity, so assuming the barrel is pointing at the same spot every time the bullet leaves the barrel (no easy task), the velocity of the bullet is key to long-range accuracy. I would be interested to hear what you consider to be acceptable velocity deviation for any given load. Obviously, the amount of deviation becomes more critical as the target distance increases. For example, using a ballistics calculator (I'm now using one from Nightforce), +/- 40 fps for my .300 Win Mag loads would equate to +/- 1/3 MOA @ 600 yards. So back to your original quiz question ... velocity may be the difference, but I won't pretend to know why one is more repeatable than the other (in terms of velocity). All I know is that the .308 is a SA round and the .30-06 is a LA round but my .300 Win Mag is a LA and it's very accurate. I look forwarding to reading your explanation.

 

[deacon8]

Ok, I can't for the life of me understand why a .308 would be more inherently accurate than a 30-06. Personally, I think it is a myth.

It is reasonable to assume that when the military replaced the 30-06 with the .308, certain long range firearms were (and are) more commonly found to be chambered in .308. Now, the military and a large amount of law enforcement agencies use the .308 as their long range choice. I believe this has simply carried over even to long range shooters. I seriously doubt that the 30-06 is purposely excluded the majority of the time.

Yeah, it doesn't make any sense to me at all. I could understand an argument in regards to ballistic co-efficiency and things of a similar nature. However, believe people too often think a .308 is more accurate because it is a myth and a "fad." After all, it's what the military and the police use right?

 

[shaggy430]

Broken record...

This topic has been beaten to death.

 

[USSR]

Broken record...

This topic has been beaten to death.

+1. Nobody who believes one way or the other is likely to be swayed. Just like the monthly "Barrel breakin" threads.

Don

 

[Bart B.]

deacon8 comments:

Ok, I can't for the life of me understand why a .308 would be more inherently accurate than a 30-06. Personally, I think it is a myth.

Here's a bit of historical fact.

In the '50's, a few accuracy buffs had used the .300 Savage to shoot 30 caliber bullets and learned that case shot 'em more accurate than the .30-06 did, albeit at a lower muzzle velocity. Sierra Bullets may well have used the Savage case to test their 30 caliber bullets as their head ballistics technician knew it shot more accurate than the '06 did. Mike Walker (Remington engineer, bench rest champ, inventor of the .222 Rem.) probably well knew this as he chose the .300 Savage case as a starting point for his crew to develop the new service cartridge for the USA armed services. That case got enlarged a bit to produce the average muzzle velocity needed as well as making the shoulder and extractor groove better withstand use in machine guns. The end result lives on.

The .308 was first allowed and used in NRA high power matches in 1963. Rifles using it immediately shot higher scores and won more matches setting new records along the way compared to the '06 shot at the same events. It was the best shots setting new records (sometimes breaking their old ones they set earlier) with their .308's instead of their former .30-06's that made the difference apparent. Lake City Arsenal also noticed test groups with both service and match grade 7.62 NATO ammo was more accurate than what the 50-year-old .30-06 produced.

By 1966, so many perfect scores shot with .308's were having to be decided by tie-breaking rules (some couldn't be broken), the scoring rings for targets used up through 600 yards had their dimensions reduced to about half. Example: the old military B target for 500 and 600 yards had a had a 12" V ring inside a 20" 5 ring; the new MR target has a 6" X ring inside a 12" 10 ring. The 200 and 300 yard target had similar ring size reductions.

Five years later, the 70-year-old 1000-yard C target had its 20" V and 36" 5 rings reduced to 10" X and 20" 10 rings on the new LR target. It was due to a combination of the .308's accuracy advantage as well as more accurate 30 caliber magnums (.30-.338 primarily) were producing better accuracy and scores than the old .300 H&H used since the late 1930's.

 

[kelbro]

It wasn't the barrels, cases, bullets, or wind bucking ability...

You left out a key component. Powder. I can't dismiss the idea that there are powders that just 'work' better and are better matches to certain case/bullet/barrel combinations. Inherent accuracy is based on the complete system. The right powder can make or break you.

I do believe that there is a combination (or more than one) where any (the 30-06 in this discussion) rifle can shoot world-class strings.

 

[USSR]

I do believe that there is a combination (or more than one) where any (the 30-06 in this discussion) rifle can shoot world-class strings.

+1. And in the .30-06's case (no pun intended), that powder is Reloader 22 with 190+ grain bullets. Once you get away from the light weight bullets and relatively fast powders that were used 40 to 50 years ago, which did not come anywhere's near to filling up the .30-06's case, you get a fill ratio that is more conducive to accuracy as well as higher velocity. Until you break away from the idea that a .30-06 needs to be loaded so as to be used in an M1 Garand, you will never see it used to it's full potential.

Don

 

[~z]

case capacity + uniformity of ignition (ie smaller powder column)

Sure, my hat is in the ring, I'm gonna sit back and learn now.
~z

 

[R.W.Dale]

Here's some info that's from the '60's and '70's for you nay sayers to take issue with.

In the '50's,

The .308 was first allowed and used in NRA high power matches in 1963.

Not to be rude but your arguments seem to be about a half century out of date and predicated on the assumption that the 30-06 must be loaded to function in a Garand.

I asked you this the other day that given two modern heavy custom bolt guns with precision hand lapped bbls firing the most modern propellants <non garand friendly> and bullets. What would be the difference. What magic would happen inside a 308 case that couldn't be recreated in a Lapua 30-06 casing

Now obviously recoil is a factor, but nowadays you have shooters pulling off some amazing feats with cartridges that make an 06 feel like a pussycat

 

[Bart B.]

USSR brings up a good point:

Once you get away from the light weight bullets and relatively fast powders that were used 40 to 50 years ago, which did not come anywhere's near to filling up the .30-06's case, you get a fill ratio that is more conducive to accuracy as well as higher velocity.

Back "then," IMR4350 easily filled the .30-06 case behind 190 and 200 grain bullets. This combination produced the best accuracy for the '06,

And 44 grains of IMR4320 filled a 7.62 NATO match case with it's 172-gr. bullet removed and a Sierra 190 put in place. This was the load used in USN and USAF converted Garands that virtually equalled the accuracy bolt guns got with 190's atop 42 grains of IMR4064; 3 to 4 inches at 600 yards.

These are not light bullets and fast powders.

And some .308's have been loaded with 250-gr. bullets with IMR4350 leaving at 2150 fps in a 1:8 twist barrels that shot about 7 to 8 inches at 1000 yards.

 

[R.W.Dale]

These are not light bullets and fast powders.

I disagree, 4320 and 4350 may have been considered slow back then, but today they are in fact fairly fast compared to other more recently developed propellants suitable for a cartridge such as 30-06 firing heavy projectiles. The past 15 yrs has see a lot of developments in the slower end of the powder spectrum.

I'm also convinced that some of the newer propellant lines such as Hodon's "extreme" series can offer better shot to shot uniformity than those old main line IMR powders

 

[sonier]

well i would say a bunch of little pansies couldnt shoot with the recoil of a 30/06. so they went to a 308 winchester

 

[USSR]

well i would say a bunch of little pansies couldnt shoot with the recoil of a 30/06. so they went to a 308 winchester

No, the .308 was a logical move, given all the usused case capacity in the '06 case. I own rifles chambered in both .308 and .30-06, and with the 150 - 175gr bullets typically used, the .308 makes more sense to me than the .30-06. That is why myself and another guy on Snipers Hide started doing extensive load development using the 190SMK and modern slow powders. What we did essentially was take away the ballistic comparison with the .308, and replace it with a direct comparison with Federal's .300WM Gold Medal Match ammo (190SMK @ 2900fps).

Don

 

[Bart B.]

sonier says:

well i would say a bunch of little pansies couldnt shoot with the recoil of a 30/06. so they went to a 308 winchester

Well, why not?

That's exactly what happened with good quality 6.5mm heavy match bullets came on the market. High power long range matches soon saw the perponderance of 6.5x.284's showing up at the matches winning all the marbles because it had less recoil. Those rifles moved less while the bullet goes down the barrel. It delt the death knoll to the 7mm and 30 caliber magnums.

 

[Zak Smith]

It delt the death knoll to the 7mm and 30 caliber magnums.

Within the confines of NRA HP rules, which prohibit muzzle brakes and suppressors.

Care must be taken when attempting to broaden conclusions made within one discipline: Do its assumptions apply elsewhere?
-z

 

[Bart B.]

Zak says:

Within the confines of NRA HP rules, which prohibit muzzle brakes and suppressors.

I'm talking about the recoil that happens before the bullet exits the muzzle.

Brakes and suppressors reduce the jet effect of gasses going out the muzzle just like jet engines operate. They have no reduction of barrel time recoil.

 

[Zak Smith]

True, however, it is relevant to the human element ("shootability") of the various cartridges, which was sonier's point.

How many fractions of an MOA accuracy are lost due to gun movement while the bullet is still in the barrel? How small of groups would someone have to shoot before it's literally in the noise?

 

[R.W.Dale]

Brakes and suppressors reduce the jet effect of gasses going out the muzzle just like jet engines operate. They have no reduction of barrel time recoil.

It's been my experience shooting braked rifles that the initial recoil pulse is a very small fraction of the entire recoil event. Otherwise brakes couldn't be nearly as effective as they are. A really good brake can tame a 300wby down to 25-06 or lower recoil levels.

Also consider the rifles being used in OTHER disciplines or even outside competition all together. Even unbraked 300wm doesn't administer much of a beating from a 18lb rifle

 

[Bart B.]

Zak's excellent questions:

How many fractions of an MOA accuracy are lost due to gun movement while the bullet is still in the barrel? How small of groups would someone have to shoot before it's literally in the noise?

Don't forget that elephant dropping double rifles have their bore axes crossing between 15 and 25 yards. This is done so their sideways movement while the bullet's going down their barrels will go straight to the aiming point at 50 to 100 yards yards. Firing the left barrel causes the rifle to swing left before the bullet exits. It's adjusted when the rifle's finished and both barrels are braized together at the best angle for the cartridge used. This is called "regulating."

Even handguns have their front sight higher above bore center than their rear sight. Pre-exit recoil moves the bore axis starting well below the aiming point to up and slightly above the aiming point as the bullet exits.

And no single barrel high power rifle has it's bore axis pointing at a point above the aiming point equal to sight height plus bullet drop at the target's range. It's always a bit lower because of recoil during the bullet's time in the barrel. Their front sight's a bit more above bore axis than the rear sight.

 

[USSR]

Personally, in F Class competition, I went from using the .30-06 (which doesn't recoil all that bad due to it's 16.5# weight) to the 6.5 Swede which is more pleasant to shoot (to say nothing of shooting flatter). Recoil has a cumulative effect on the shooter, and if you can reduce it without losing performance, I'm all for it.

Don

 

[R.W.Dale]

Zak's excellent questionson't forget that elephant dropping double rifles have their bore axes crossing between 15 and 25 yards. This is done so their sideways movement while the bullet's going down their barrels will go straight to the aiming point at 50 to 100 yards yards. Firing the left barrel causes the rifle to swing left before the bullet exits. It's adjusted when the rifle's finished and both barrels are braized together at the best angle for the cartridge used. This is called "regulating."

Even handguns have their front sight higher above bore center than their rear sight. Pre-exit recoil moves the bore axis starting well below the aiming point to up and slightly above the aiming point as the bullet exits.

And no single barrel high power rifle has it's bore axis pointing at a point above the aiming point equal to sight height plus bullet drop at the target's range. It's always a bit lower because of recoil during the bullet's time in the barrel.

But this is all irrelevant in the context of this 30-06 vs 308 discussion as 308 suffers from this same phenomena as well, you speak as though 308win is immune to in bbl recoil while 06 is eat up with it. All said I doubt the actual figure would be greater than 5%

 

[Zak Smith]

And no single barrel high power rifle has it's bore axis pointing at a point above the aiming point equal to sight height plus bullet drop at the target's range. It's always a bit lower because of recoil during the bullet's time in the barrel. Their front sight's a bit more above bore axis than the rear sight

If I am reading this right, you claim a fixed correction regardless of target range that compensates for this movement, and the only way to test would be to lock the gun in an immovable vise and shoot it, then compare to the POI when shot the normal way?

I am still interested to know how small of groups I need to shoot with a braked/suppressed 7/30/338 before the pre-bullet-exit gun movement does not affect group size-- IE, what is the claimed accuracy decrease.

 

[Bart B.]

Zak asks:

I am still interested to know how small of groups I need to shoot with a braked/suppressed 7/30/338 before the pre-bullet-exit gun movement does not affect group size-- IE, what is the claimed accuracy decrease.

Zak, I see I didn't answer that question very well before. Here's a better answer.

You'll probably need to shoot the rifle from a machine rest eliminating all human elements that open up the group. Such tests do eliminate all human elements and only test what the rifle can do.

Note that after the bullet's left the muzzle, any movement of the rifle has no effect on its trajectory. But there may be a microscopic amount if there is rifle movement caused by the brake/suppressor as the exited bullet goes near its hardware and the gas direction bouncing off them somehow changes the bullet's path.

That's a good question. The above's my theory on it based on what I know.

 

[USSR]

You'll probably need to shoot the rifle from a machine rest eliminating all human elements that open up the group.

Or get the keys to the Houston warehouse.

Don