Given the larger case capacity, if the .30-06 is handloaded to the same pressure as the .308W, and fired in a modern, strong action, what should be the velocity gain? Say, as a percentage or in FPS with say, 150 g bullet? BTW, I'm not trying to start an argument about which round is better. Just trying to gain a lil scientific information.

Scientific information: At equal pressure, more cubic inches equals more power.

How much additional "power" differences exist between those two good cartridges varies by the reloader's nerves because we can't measure the pressures and no loading book is going to give us higher than SAAMI pressure suggestions.

Try to find the numbers for the old Hornady Light Magnum loads. That's basically what they were, above SAAMI book pressures. But it was done in a controlled setting with plenty of availability of tools/methods to test every aspect for safety

Agreed, once you start loading over SAAMI pressure specs you are basically in the same position as a 'wildcatter'. The difference in SAAMI specs is only 2,000 psi. That pressure only specifies the (average) maximum, however, it is the entire pressure 'curve' that will determine the muzzle velocity. So the results depend on alot more than just 2,000 more psi peak pressure.

I show the 06 as 60,000 and the 308 as 62,000 with a 180gr bullets that equats to about 30fps and .5gr of powder increase in the 06 taking it to 308 pressure.

So since the 270 and 25-06 were taken to 65,000 for max pressure in a normal bolt rifle I see no reason not to take any 06 based case to the same pressure. Yes that is over standard. But since 99.99% of us have no pressure equipment are we really loading to 60,000 or 65,000 in our specific rifle????

Ramrod makes a good point. Going by book loads, do we even know if we are reaching factory ammo pressures in the first place? Weatherby, for example. Its NOT easy to get Weatherby/Norma speeds with what's listed in "books". Plus not to mention pressure differences between "tight" chambers, different thickness levels of brands of brass...so on and so forth.

I figure, if you're not seeing classic signs of over pressure, there is no real reason to stick to original low pressures IF that is what you want to do, and you don't have some old soft rifle. A current R700 .257 Roberts and 25-06 are made in the same factory, from the same steel, with basically the same exterior rifle dimensions. Yes, SAAMI is much lower on the .257, but its not like Remington is going to make "hard" or "soft" rifles dependant on cartridge chambering.

Saying that though, as always, be careful and feed your rifle how IT likes to be fed. Heck my factory .270 shows high pressure signs with faster premium FACTORY loads lol. Tight chamber.

Just answering the question as stated and forgetting everything else ,and just saying the pressures are equal the full excursion of the barrels in say two 22" barrels the difference would only be 11 ft./sec. because the volumes would be 33.68 cc compared to 32.68 cc. Looking at this I'm sure that wasn't the sought answer. roger

quote:

Originally posted by MileHighShooter:
Ramrod makes a good point. Going by book loads, do we even know if we are reaching factory ammo pressures in the first place?

One of the most thought provoking stickies here.
http://forums.accuratereloadin.../2511043/m/316101735

Check all the reloaded data vs the SAAMI spec ammunition reference. Look at the pressures and veocities achieved, compare it back to the SAAMI spec reference load.
Cheers...
Con

quote:

Originally posted by No Plea:
Given the larger case capacity, if the .30-06 is handloaded to the same pressure as the .308W, and fired in a modern, strong action, what should be the velocity gain? Say, as a percentage or in FPS with say, 150 g bullet? BTW, I'm not trying to start an argument about which round is better. Just trying to gain a lil scientific information.

I do load both the .308W and the 30-06 and I also measure pressure with an Oehler M43. When both cartridges are loaded to potential (100% loading density/not necessarily the same powder in each cartridge) and equal pressure the 30-06 with 150 gr bullets will give upwards of 150 fps more velocity given equal barrel lengths.

The data for the above answer comes from 2 A&B 24" barrels with match cahmbers headspaced to minimum spec. While the '06 barrel has a shorter effective barrel length it also has a greater case capacity. This greater case capacity allows, with the correct powder, more available energy to push the equal make and weight bullets to a higher velocity.

As an example I found that Federals 150 gr Powershok's in both .308W and 30-06 give close to the same psi. However, the .308W cartridge held 46.3 gr of a ball powder and the '06 cartridge held 53.5 gr of an extruded powder. The .308W was laoded pretty much to 100% density but the '06 still had perhaps 15% more capacity. The '06 gave 51 fps more velocity with more powder.

Thus we see we had more romm for more powder in the '06. So if we used more of a slower powder in the '06 to get to 100% loading density and the same psi as the .308W the velocity would be higher in the '06 because there was more available energy to push the bullet.

I use 165 Hornady SPBTs loaded to the same psi in both the .308W and the '06. I get 180 fps more out of the '06 than the .308W when both are loaded to 60,000 psi(M43).

I load the 190 gr Hornady SPBT to 2700 fps at 62,000 psi(M43) in my 24" barreled M70. In the test A&B .308W barrel I can barely break 2500 fps at the same 62,000 psi(M43). The '06 obviously has the greater advantage, given equal psi and equal barrel length, as bullet weight increases. That is a great elk load BTW.

The soon to be available high energy powders from Hodgdon will no doubt allow the .308W catch up to the '06 (loaded with current powders). However, loading the '06 with those high energy powders may allow the '06 to sneak up on current .300 H&H, .300 Win Mag and the .300 WSM mag velocities with 150 -180 gr bullets given equal barrele lengths and psi's. How close the '06 can sneak up on them remains to be seen.

Larry Gibson

I think the hot rodders had the perfect explanation, "There's no substitute for cubic inches."

Jerry Liles

I'm with Jerry and Larry. From my limited experience with these two cart. I would expect around 130 fps at least with 24" barrels.

The 308 holds about 53.5gr H2O, the 30-06 holds about 68gr. That 14.5gr difference is about 27%. a 27% difference in case capacity will yield about a 6.5 to 7% increase in velocity, all other things being equal.

you would in effect have the same cartridge.

however, the greater amount of gas generated by the greater powder volumne should produce higher velocity.
you would have to have equal bbl lengths [from the case mouth] to test how much.

The question assumes that everything is equal which it is not. The issue has packaging differences including the rifled barrel lengths which gives a half an inch to the 08 assuming both use the same length barrels.

Based upon your stated question there should be no gain what so ever assuming that you use a 21.5" barrel for the 08 and a 22" barrel for the 06. That meaning the 60,000 psi of pressure is pushing a 150 grain bullet down each barrel.

That would be to easy right.

There is a factor of burn time which gives an edge to the 08 for getting to the 60000 psi the quickest which is why the 08 cases do so well in shorter barrels and the 06 cases don't.

It's like watching a drag race between a big block chevy vs a small block chevy. The small block beats the big block out of the gate but the big block has greater pull over distance.

It is impossible to calculate the actual difference without truly eliminating the variables.

quote:

the 30-06 with 150 gr bullets will give upwards of 150 fps more velocity given equal barrel lengths

That's been my experience as well (150 fps or a bit more)... For whatever reason, the gap seems to narrow a bit with 165's. Less than 150 fps difference is usually the case IME.

quote:

Originally posted by ramrod340:
I show the 06 as 60,000 and the 308 as 62,000 with a 180gr bullets that equats to about 30fps and .5gr of powder increase in the 06 taking it to 308 pressure.

So since the 270 and 25-06 were taken to 65,000 for max pressure in a normal bolt rifle I see no reason not to take any 06 based case to the same pressure. Yes that is over standard. But since 99.99% of us have no pressure equipment are we really loading to 60,000 or 65,000 in our specific rifle????

In theory the max loads shown in reloading manuals are at, or very near, the max (average) peak pressure limit. So if you exceed those loads, you will be over the pressure limit. But unless you are testing the pressure yourself, you won't really know by how much.

quote:

Originally posted by Larry Gibson However, the .308W cartridge held 46.3 gr of a ball powder and the '06 cartridge held 53.5 gr of an extruded powder. The .308W was laoded pretty much to 100% density but the '06 still had perhaps 15% more capacity. The '06 gave 51 fps more velocity with more powder.
Larry Gibson

Larry! I agree with your analogy but when using the 2937fps in the .308 and adding 14% more powder if we get close to a complete energy differential transfer* we would see the 30-06 at around 3135.8 fps.

* Probably not attainable but I think mathematically close. roger

But the difference between the 2 really tips in favor of the 30-06 with 180 grain bullets or heavier. With a 180/ and 4350 in the 30-06, once can obtain 2850-2900 fps, and still be within safe pressure limits. I believe with the 308, because the case capacity is diminished by the longer bullet, 2500fps or so is what you can expect. Still no slouch at 300yds or less, but now you are at a negative of 300 fps. Significant, I'd say.

Jerry

quote:

Originally posted by Jerry Eden:
But the difference between the 2 really tips in favor of the 30-06 with 180 grain bullets or heavier. With a 180/ and 4350 in the 30-06, once can obtain 2850-2900 fps, and still be within safe pressure limits. I believe with the 308, because the case capacity is diminished by the longer bullet, 2500fps or so is what you can expect. Still no slouch at 300yds or less, but now you are at a negative of 300 fps. Significant, I'd say.

Jerry

That's absolutely NOT been the case with the four 22" bbl'd 30-06's and eight 308's I've loaded for.

With 4350's I've never been able to safely get beyond 2,780 with 180's (22" bbl). Most 308's will run 180's in the 2,630 - 2,660 range... the 150 fps rule is still firmly in place with 180/165's. What I have noticed is the 30-06 handles 150's closer to 200 fps faster than the 308.

Counter intuitive likely, but those have been my findings over the years...

that don't make things equal then. you are limiting the 308 by magazine length.
if you seated the bullets to no deeper than the bottom of the neck and had the throat cut for the heavier bullet it would equalize things up considerably.
it's what kills many cartridges like the 257 roberts, the 6mm remington also both based on the 7 mauser case.
equal bullet weight over equal pressure would make the same velocity.
the only way there would be a difference is in gas volumn.

quote:

equal bullet weight over equal pressure would make the same velocity.

Nope...

quote:

Originally posted by Jerry Eden:
But the difference between the 2 really tips in favor of the 30-06 with 180 grain bullets or heavier. ...

+1 Jerry is absolutely correct.

quote:

Originally posted by Hot Core:

quote:

Originally posted by Jerry Eden:
But the difference between the 2 really tips in favor of the 30-06 with 180 grain bullets or heavier. ...

+1 Jerry is absolutely correct.

No, Jerry is incorrect. I realise that HC neither cares for chronographs, Oehler's M43 or me but that assumption, though common, is not correct. Using actual measurement of loads with equal pressures in equal barrels (both A&B 24" barrels on M98 actions so seating depth was only restricted by the throats. The chambers were both cut with match reamers for the 175 MK bullet so seating depth outside the case mouth is practically identical) shows the '06 has a larger velocity gain with the lighter weight 150 and 165 gr bullets. I suppose one could juggle that around to percentages or something to show otherwise but from a pure fps perspective the gain is more with the lighter weight bullets.

Larry Gibson

Larry - If you still had access to those rifles it would be interesting to see the differences with 200gr and 220gr bullets.

quote:

Originally posted by Larry Gibson:

quote:

Originally posted by Hot Core:

quote:

Originally posted by Jerry Eden:
But the difference between the 2 really tips in favor of the 30-06 with 180 grain bullets or heavier. ...

+1 Jerry is absolutely correct.

No, Jerry is incorrect. I realise that HC neither cares for chronographs, Oehler's M43 or me but that assumption, though common, is not correct. Using actual measurement of loads with equal pressures in equal barrels (both A&B 24" barrels on M98 actions so seating depth was only restricted by the throats. The chambers were both cut with match reamers for the 175 MK bullet so seating depth outside the case mouth is practically identical) shows the '06 has a larger velocity gain with the lighter weight 150 and 165 gr bullets. I suppose one could juggle that around to percentages or something to show otherwise but from a pure fps perspective the gain is more with the lighter weight bullets.

Larry Gibson

HotCore is the biggest wannabe on this board... never contributes anything of concrete substance.

And yes, no offence to Jerry, but as I stated earlier I believe he is absolutely incorrect, popular notions aside. My experience totally contradicts his assumptions.

Two cartridges one a 308 and the other a 30-06, fired from same length barrel, identical bullet, both loaded to same Peak Chamber Pressure.

In theory in an " ideal gun" both could have the same Pressure at base of bullet just prior to bullet egression.

The velocity would not be the same!

Why?

The difference in the magnitude of the Specific Impulse and the difference in the Piezometric Efficiencies between the two cartridges.

The 30-06 Would most likely if loaded with the most efficient propellant for expansion ratio reach a higher velocity than the 308 under same condition at the same Peak chamber pressure and the same Pressure at bullet base at time of bullet egression.

The position of "burnt" would be different for the two cartridges

In plain terms the time over which presssure is applied in the chamber and in the barrel is by necessity different between a 30-06 and 308, thus the 30-06 would accelerate to a higher velocity than the 308 in the same barrel under the same peak chamber pressure and same peak barrel pressure.

Another way to validate this theory would simply be to look at thermochemistry of the scenario.

The 30-06 would have greater total potential energy than the 308 and if both have equal losses or near equal losses in energy; the 30-06 would have a greater kinetic energy for the same bullet than the 308.

Ballistic efficiency in a ideal gun would have it that both bullets retain appoximately 33% of the total potential Energy in the form of kinetic energy once combustion has taken place. And this could be at equal peak chamber pressure and Pressure at base of bullet at time of bullet egression.

The rule of thumb is .30-06 will always have a 100..150fps advantage over the .308 w/ equal pressure. Since the .30-06 has more to burn, the "curve" goes to the .30-06 for generating a more even pressure on 180+ gr bullets of identical construction, but it is not always True. In a theoretical world, sure. I'm more partial to the .30-06 Vs 8x57 argument!

Even though you might have equal peak pressure the P-V diagrams or curves will differ. The 06 diagram will have a greater area (ENERGY) under the curve than the .308. Voila greater velocity. It will definitely be more evident with heavy for caliber bullets roger

I have a number of identical rifles in both calibres, remington 700s 22 inch barrels. Both have one in ten twists. I have no pressure measuring equipment, but I do watch all signs carefully. With the Remingtons in the 308 with 150s I get accurately with fairly high pressures 2750. with the 3006 and what appears to be the same pressures about 2975. same bullet, same primer different powder.
With 180s in the 308 I get 2540. In an identical model 700 Remington in 3006 with the same 180 winchester power point used in the 308 I get 2750, with what appears to be somewhat less pressure, based on primer flatness and case life. The 3006 may have gone faster if I pushed but I was after accuracy loads.

All the theory one can muster can't hold a candle to the results of experimentation in the real world.

Larry said:

quote:

Using actual measurement of loads with equal pressures in equal barrels (both A&B 24" barrels on M98 actions so seating depth was only restricted by the throats. The chambers were both cut with match reamers for the 175 MK bullet so seating depth outside the case mouth is practically identical) shows the '06 has a larger velocity gain with the lighter weight 150 and 165 gr bullets.
- - - - - - - - - -
However, the .308W cartridge held 46.3 gr of a ball powder and the '06 cartridge held 53.5 gr of an extruded powder. The .308W was laoded pretty much to 100% density but the '06 still had perhaps 15% more capacity. The '06 gave 51 fps more velocity with more powder.

Let's look at a few of things Larry tells us. First, different types of powders with different burning rates were used. Second, two different quantities of the powders were used. Third, the .308 case was filled to capacity with powder but the .30-06 case was loaded to 85% capacity and had a 15% void. Given differences like those, it is easy to see how the real world increase in velocity could be 50fps instead of an expected 150-200fps.

But why not use the same powder? Could it be that in the practical world there is no one powder that can fill both cases to 100% capacity without producing excessive pressure in one or the other?

And, when talking about the theoretical, we still haven't heard about the greater loss of efficiency in the faster bullet due to increased heat/friction or the additional energy required to cause one bullet to rotate on its axis faster than the other. Or the effect of the different volumes of the respective pressure vessels. Or, for that matter, whether any powder in either cartridge would have the critical minimum L/D in the powder column required to achieve an optimum pressure wave with that specific propellant. There are so many theoretical variables to consider.

Nope, all the theory one can muster can't hold a candle to the results of experimentation in the real world.

quote:

HotCore is the biggest wannabe on this board... never contributes anything of concrete substance.

Something we can all agree on.

quote:

All the theory one can muster can't hold a candle to the results of experimentation in the real world.

?????????

Theory is the result of real world experimentation and observation !

I would venture that the foundation of our hobby and craft is directly or indirectly a result of ballistics theory.

The data of Each and every commercial load manual ever produced by a bullet or powder company is the result of calculations based on a theory.

In fact the coming about of each and every military cartridge, bomb, cannon projectile or rocket adopted by the US in the 20th century was founded in calculation based on theory.

The basis for calculation used in the first half of the 20th century as it pertains to small arms munitions in the US was Coppocks method, hence the propencity of load manuals to overestimate velocity and underestimate actual pressure.

The guru's of handloading, Ackley, Powley, Waters all were practitioners of Coppock, all of the popularly used "rules of thumb" of handloading are derivatives of Coppock.

brad:
you forgot the second sentence there.
the only way there is a difference is in gas volumn.
more molecules pushing longer.
same thing as necking a case up, more guys pushing the truck.
if thhe question were a 150 in the 308 and a 150 in the 338-08.
making things equal. powder, case,bbl length.
would the 338 be faster?
it should be.

quote:

Originally posted by ALF:
The data of Each and every commercial load manual ever produced by a bullet or powder company is the result of calculations based on a theory.

No, tests are conducted, rounds are fired, pressures measured, velocities measured, and actual results are used to formulate the tables. Even ballistics tables are extrapolations based on actual tests. Have you ever heard of an accurate calculation for "coefficient of form"?

quote:

In fact the coming about of each and every military cartridge, bomb, cannon projectile or rocket adopted by the US in the 20th century was founded in calculation based on theory.

Only to provide a starting point and the starting point is never the same as the ending point. Real world testing, experimentation, and evaluation makes the difference.

quote:

The basis for calculation used in the first half of the 20th century as it pertains to small arms munitions in the US was Coppocks method, hence the propencity of load manuals to overestimate velocity and underestimate actual pressure.

You said it yourself. The calculations differed from real world pressures and velocities. The works of Coppock (1940s) and others were especially important because they could not easily and accurately take measurements with the tools of their day. But that changed in the 1960s with the development of piezoelectric crystal gauges and in the 1970s with the development and use of instruments to provide in-bore data throughout the interior ballistic cycle.

For anyone wanting to make his own use of Coppock's Advanced Internal Ballistic Model they can get it here, have at it!

Coppock's Advanced Internal Ballistic Model


Powley's equations (also used by Load From A Disk) and Powley's computer are the result of observed data and extrapolation. Yet they still only provide approximations, sometimes good and sometimes way off. QuickLOAD and QuickTARGET are more accurate at predicting internal and external results because they use software simulation. QuickLOAD mathematically predicts the gas pressure and the velocity of the bullet at every fraction of a millimeter down the barrel. QuickLOAD can vary considerably from actual measure pressures listed in load books. You can find other prediction software but it does just that - it predicts. Here is what one engineer, Karl W. Kleimenhagen, so eloquently says about such things, "Caution - The internal ballistics of small arms are nearly impossible to predict. Small changes in bullet construction will change how readily the bullet enters the bore. The more difficult it is to engrave the bullet, the higher the pressure grows. The greater the pressure gets to be, the faster the powder begins to burn. Pressures can and do rise unexpectedly fast. Another big factor is the primer, for it determines the initial rate of pressure rise, and thus how fast the burning accelerates. Powder lots sometimes vary greatly in burning "speed" as well. Because the variability of bullet engraving, primer ignition, and powder lots are difficult to quantify, all commercial internal ballistics software simply ignores these effects. Such software can help you select a powder, but it cannot tell you how much of it to use nor which primer to use. It also can't tell you what fps you can reliably expect to get at a given pressure."

Please do not misunderstand me. I fully agree that prediction software, calculations, and tables are very useful for working up beginning loads and making approximate predictions of results. Nevertheless, no amount of paper calculation and prediction can equal the actual, real world information you get conducting actual live-fire tests. Too many variables exist. Larry's results with 175gr SMK in the .308 and .30-06 just bring the point home.

A very good read is A Brief Journey Through the History of Gun Propulsion from the Army Research Institute (ARI). It is available online here:

A Brief Journey Through the History of Gun Propulsion .

More technical materials are The Bullets Flight by Franklin Mann, Understanding Firearms Ballistics By Robert Rinker, and Aerospace Ordnance Handbook by Frank Pollard and Jack Arnold, Jr.

Grenadier:


Thank you for that and this is why one can calculate peak chamber pressure in a particular gun using a chronograph !!!!!!!

( within reason of course giving credence to statistical treatment of data and given knowledge that ballistics is a purely stochastic endeavour ie no value is absolute, not even a values measured directly by whatever means, or device chosen...... Even measurement of the case head using a micrometer )

quote:

Originally posted by Larry Gibson:
trying to gain a lil scientific information.

I do load both the .308W and the 30-06 and I also measure pressure with an Oehler M43. When both cartridges are loaded to potential (100% loading density/not necessarily the same powder in each cartridge) and equal pressure the 30-06 with 150 gr bullets will give upwards of 150 fps more velocity given equal barrel lengths.

[/QUOTE]

My results have been similar although I was taking the loads just before accuracy fell off and in bench style rifle with switch barrel. Actually my difference was a little greater than 150 f/s and I put that down to powder suitability and also in my experience cartridges with larger case capacity for the bore size retain accuracy to higher pressure.

Actually the biggest velocities differences I had with 308 and 30-06 were with 130 grain bullets, specifically the 130 grain Speer Hollow point and no doubt this related to powder. I had Australian powder that was like 3031, 4064 and Win 748 and Win 748 gave me the best results for accuracy. Velocity was 2950 with 52 grains of 748. In the 30-06 Win 760 gave 3250 plus.

Brad:

I am absolutly CORRECT. If you give 50fps for each additional 1" of barrel length the 100fps, substansiates my previous statement. All the 30's I have run over the cronograph, lead me to believe the guys who want the 308 to run with the 06, are wishfull thinkers. No knock, just fact.

Jerry

Mike

Your results are pretty much the same as mine. I load for numerous '06s and .308Ws and the difference is pretty consistent rifle to rifle. Many believe the biggest difference will be with heavier bullets but i also have found that not to be the case. I mentioned that on the other thread of similar topic. The greatest velocity difference is most often with the lighter bullets with the '06 having a decided advantage over the .308W, given equal barrel lengths and pressures.

Thanks for the additional input.

Larry Gibson

quote:

Originally posted by Larry Gibson:
Mike

Your results are pretty much the same as mine. I load for numerous '06s and .308Ws and the difference is pretty consistent rifle to rifle. Many believe the biggest difference will be with heavier bullets but i also have found that not to be the case. I mentioned that on the other thread of similar topic. The greatest velocity difference is most often with the lighter bullets with the '06 having a decided advantage over the .308W, given equal barrel lengths and pressures.
Thanks for the additional input.Larry Gibson

Larry, with all due respect, can you explain the physics of why this is true. I for one am mystified. For example ,if a 220 gr. bullet is stuffed into a .308 case using up powder room it seems that comparative performance to an identical bullet in a 30-06 would be demonstrative to a greater degree than say two 110 gr. bullets. What am I missing here? roger

barsche

If you figure the % difference then the difference between heavy and lighter weight bullets are pretty close to the same. However the lighter bullets will be using faster burning powders and the '06 capacity with faster burning powders makes the difference in a larger gain when just fps are considered.

Not sure of the "physics" involved other than you can use more of the faster burning powders in both cases keeping the psi's equal. The powder, the more "work" that can be done, hence they push the lighter weight bullets faster.

I'm sure the "the '06 works better with heavier bullets" is a hold over from before chronographs were available or from just taking loading data velocities out of manuals as "proof". The fact, when psi and barrel lengths are equal, is contrary to the popular and long held notion.

Larry Gibson