If a guy loads some cartridges with everything being the same except the powder and charges, will cartridges loaded with a fast powder and cartridges loaded with a slow powder that have the same MV (2700 fps)have the same downrange ballistics?

quote:

have the same downrange ballistics

Unless I'm misunderstanding the answer is YES.

Same MV equals same downrange V and Drop

Same cartridge same bullet same MV equals same downrange

Yes, the external ballistics of the bullet are unrelated to the internal ones; i.e., the bullet reacts to the laws of gas pressure dynamics, (and other factors like twist rate and bore diameter), but once it leaves the muzzle, it can only follow the laws of gravity (of course other outside factors like wind). So, the bullet dos not know how it got to 2700 fps, it just is there.
The shooter will know, though, as slow powders produce more recoil than fast ones do. Because you are using more of it.

I think the correct answer would be "it depends". does the slower powder take longer time in the bore? If so, recoil would be acting on the rifle longer-giving more muzzle lift and thusly affecting the POPI- AFAs once the bullet is free from the muzzle- indeed, it would follow the same path, all else being equal. I doubt it is.

This is why we may see 30 cal 165s on top of 4895 having a different POI than the same on top of 4831 even tough they chronograph at the same velocity...

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a different POI

I see POI and Ballistics being a completely different issue. I've had faster powders hit higher and lower. I've never seen a rule of thumb that I would bet a on that faster will hit higher with same MV.

I "ASSUME" that his question was slow or fast same MV sighted to same downrange point would all other ballistics would be the same.

Barrel harmonics = different impact points with same muzzel velocities but different burn speeds of powder

Downrange balistic are identical if 3 things are equal

Bullet weight
BC
Muzzel Velocity

Downrange ballistics and POI are two different things

That's really questions around three subjects

internal ballistics -- of course that changes

external ballistics -- doesn't change much, with same bullet, you should reasonably have identical external ballistics

bullet path - a questions of barrel harmonics, precision, and bullet flight, as barrel harmonics COULD change the bullet flight

now, as for accuracy -- that could change -- poi could change, groups could shift, and perhaps even with a combo of all three, group size change

By Golly I think Jeffs got it!!! roger

quote:

By Golly I think Jeffs got it!!!

Man don't say that you will give him a big head.

But I would agree he pretty much hit the nail on the head.

The theory and practice of internal ballistics delineate slow vs fast powders based on the concept of "position of burnt" in the barrel.
A "fast " propellant will have a position of burnt close to the chamber whilst "slow" propellants have the position of burnt far down the bore close to the muzzle.

The effects are apparent in velocity and in precision of shots. When position of burnt is far from the muzzle muzzle blast has less of an effect on projectile stability at egress.

Application of fast propellant guns are found in Howitzers where intershot variation need to be small as to ensure downrange precision.

This in opposition to slow propellant guns where the position of burnt is close to the muzzle. Typically tank and antitank guns. They have higher muzzle velocities but relatively less precision. They have a large muzzle blast and the effect of muzzle blast is more apparent on projectile stability at muzzle egress.

Guns are actually designed in practice to fit this principle.

As ballistics is scalable we can assume that the same holds true for shoulder fired arms however due to the scale difference the magnitude of actual effect is less apparent.

quote:

Originally posted by Pegleg:
the same MV (2700 fps)have the same downrange ballistics?

YES.. The same MV is the same MV, regardless of how it is achieved. That is of course, as long as it is the same projectile. Otherwise all of the mountains of ballistic data based on muzzle velocity and Ballistic coefficients would be useless. Maybe the OP needs to define what he means by "downrange ballistics". Because when we take things like barrel harmonics into consideration, no two rifles are EVER the same!

Same bullet same muzzle velocity does not equate to exactly the same downrange ballistics.

The assumption is that the bullet exits the barrel in exactly the same attitude ( angle of attack) thus having the same drag profile with each shot. This is assumed in each and every ballistics calculator.

Reality is that it does not ! Thus right from barrel exit the drag profile for each shot differs albeit very small.

This then means the time from shot to impact is not the same as point of impact cannot be the same. The time it takes from the bullet to "come to rest " is not the same. This accounts then in part for what we see as the "group pattern " on the target downrange. If everything was exactly the same the bullets would all go through the same hole.


Bullet egress from the barrel is random in terms of angle of attack ( angle between long axis of the bullet and the line describing direction of flight) For each barrel and each load there is a randomness that varies from zero to a certain angle value.

Precision loading techniques aim to decrease the limits of this randomness but cannot fully eliminate it.

Proof of this randomness of angle of attack was discovered relatively recently when experiments were conducted to try and explain why some close up shots would cause very large devastating wounds in some instances and others not.

Using Doppler radar and high speed spark shadow photography projectile egress angle of attack could be shown and measured and this then correlated with downrange data.

Im glad we sorted that out. Now someone from AR needs to phone virtually every bullet and powder manufacturer that has ever made a reloading manual and inform them that the ballistic data they have been compiling for the last two or three generations has all been a waste of time.

Powder and ammo company ballistics data as published in manuals :

Real or mathematically derived ?
Pressure data ? Real or mathematically derived ?

What about the endless pages and tables of downrange ballistics: Real or calculated ?

Each and every load with each and every bullet in every caliber published: Real or mathematically derived ?

Testing does take place but even that is subject to statistical analysis.

Is their data wasted , no ? in fact very valuable but if anyone thinks they actually shot every load and physically measured the data you are sadly mistaken.

Because the ballistics event ( internal, intermediate and terminal) is entirely stochastic at every level real time measurement becomes a game of statistics.

quote:

Originally posted by ALF:


Is their data wasted , no ? in fact very valuable but if anyone thinks they actually shot every load and physically measured the data you are sadly mistaken.

Because the ballistics event ( internal, intermediate and terminal) is entirely stochastic at every level real time measurement becomes a game of statistics.

Thank you for so eloquently making my point.. I too am certain that much of their data is mathematically calculated. But I am also certain that they have physically measured enough loads to feel quite comfortable about publishing such data. And now, I believe we have come full circle.

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Originally posted by Wstrnhuntr:

quote:

Originally posted by ALF:


Is their data wasted , no ? in fact very valuable but if anyone thinks they actually shot every load and physically measured the data you are sadly mistaken.

Because the ballistics event ( internal, intermediate and terminal) is entirely stochastic at every level real time measurement becomes a game of statistics.

Thank you for so eloquently making my point..

Which basically means your own results are better, for you, than theirs

Every time we weigh a load, measure a shots velocity, every time we pull a trigger on a load we have to cognizant of the fact that "The Universe is Stochastic and Non linear" to paraphrase Larry Sturdivan formerly of the Aberdeen Proving Ground.

I enjoy reading your post's Alf. They always remind me, "this is the type of man that made landing on the moon and coming back home possible."
Reminds me that the hysterical "facts" that are presented on behalf of one political view or another are just that, Hysterical.
"The Universe is Stochastic and Non linear" to paraphrase Larry Sturdivan formerly of the Aberdeen Proving Ground

quote:

Originally posted by ALF:
The theory and practice of internal ballistics delineate slow vs fast powders based on the concept of "position of burnt" in the barrel.
A "fast " propellant will have a position of burnt close to the chamber whilst "slow" propellants have the position of burnt far down the bore close to the muzzle.

The effects are apparent in velocity and in precision of shots. When position of burnt is far from the muzzle muzzle blast has less of an effect on projectile stability at egress.

Application of fast propellant guns are found in Howitzers where intershot variation need to be small as to ensure downrange precision.

This in opposition to slow propellant guns where the position of burnt is close to the muzzle. Typically tank and antitank guns. They have higher muzzle velocities but relatively less precision. They have a large muzzle blast and the effect of muzzle blast is more apparent on projectile stability at muzzle egress.

Guns are actually designed in practice to fit this principle.

As ballistics is scalable we can assume that the same holds true for shoulder fired arms however due to the scale difference the magnitude of actual effect is less apparent.

let's catch that before alf deletes it

Dr Alf, whilest stretching this into utterly-unlike-stated-question-likely-has-truth, it has nothing to do with the question of "adjust fast/slow powder, in the SAME gun, to the same vel, what would the result be"

(sigh) - ex-spurts

The answer remains the same even if the muzzle velocity is the same ( 2700) fps the downrange data will not be the same.

The reason lies with the concept of Peizometric efficiency as first coined by Serge Zaroodny of the Aberdeen Proving ground. This refers to the ratio of barrel pressure to chamber pressure.
ie high vs low efficiencies.

Ultimately t is all about drag and the drag on a projectile driven from a propellant with position of burnt close to muzzle is different to the drag of a projectile where position of burnt is close to chamber.

The reason lies in the effect of muzzle blast on projectile stability. Carlucci pages 163 to 165

High efficiency loads are those loaded with slow propellants where the barrel pressure is high relative to chamber and position of burnt is close to muzzle.

The muzzle blast is bigger than than that of the low efficiency load ( ie fast powder) where the blast is smaller.

Corner page 142 and on expands on this.

The bullet may have the same muzzle velocity but the initial disturbance on stability is larger for the high efficiency load hence then a larger initial drag effect until disturbances are damped out.

So Alf, if we isolate this (burn position) variation alone in, lets say a hypothetical 30-06 launching a 180 gn bullet using first 4895 to achieve 2700 fs and then using 4350 to achieve the same MV. Roughly how much potential variation on paper @ 100 yds are we talking about? Or is that something that is even theoretically equatable?

Dont know if a specific test has been published to look at this point specifically.

What is out there is that the internal ballistics cycle of the 7.62 NATO has been established. There are various models by which this is done. We can, by using various tools and models accurately determine where point of burnt is for each propellant.

There is a whole library of data on the intermediate ballistics cycle of the 7.62
(.308) bullet.

Lastly we have a whole science with it's own language on the egress of a projectile from the bore of guns including the effects of muzzle brakes and suppressors on projectile accuracy.

There is ample evidence to support that muzzle blast magnitude and turbulence effects projectile stability.

We have ample evidence that position of burnt effects muzzle blast. Linking the two is simple and is a essential part of gun design for military application.

Interesting. Thanks for the reply. Do you think that a faster burn would have a more consistent burn position than a slower propellant in regards to small arms? Especially if there isnt enough bbl to completely burn the slower powder?

Chamber pressure would be greater with the faster burn rate than with the slower burn rate. It's all about monument relative to pressure. Commonly Muzzle velocity isn't measure at the Muzzle but around 15 feet forward, and if you want to get precise then back calculated based on the distance between skyscreen sets and the muzzle. Relative, if velocity is the same, back calculation would be the same, along with forward calculation if BC of the bullet in question is the same. Here is the fly in the ointment, Rounds of factory ammo in a box can vary as much as 15 fps +/-, and it is about impossible to get even the most careful handloads much under that variance. Just to many factor involved.

I think the pressure curves would be different, slow powder would be still accelerating, faster might have peaked before the bullet exited the muzzle.

The Oehler 43 measures pressure curves as well as the pressure itself in an offset fashion. You must fire a factory load or two to get that pressure and MV. It then will compare your loads against that offset (factory pressure curve).

It does this by having a strain gauge epoxied to midway of the chamber.

He invited me to attend a session of his Chronograph school one summer. Pretty neat stuff.

what jeffe said

quote:

Originally posted by jeffeosso:
That's really questions around three subjects

internal ballistics -- of course that changes

external ballistics -- doesn't change much, with same bullet, you should reasonably have identical external ballistics

bullet path - a questions of barrel harmonics, precision, and bullet flight, as barrel harmonics COULD change the bullet flight

now, as for accuracy -- that could change -- poi could change, groups could shift, and perhaps even with a combo of all three, group size change

and, in case you have a REALLY impressive collection of data...

quote:

Originally posted by ALF:
The answer remains the same even if the muzzle velocity is the same ( 2700) fps the downrange data will not be the same.

The reason lies with the concept of Peizometric efficiency as first coined by Serge Zaroodny of the Aberdeen Proving ground. This refers to the ratio of barrel pressure to chamber pressure.
ie high vs low efficiencies.

Ultimately t is all about drag and the drag on a projectile driven from a propellant with position of burnt close to muzzle is different to the drag of a projectile where position of burnt is close to chamber.

The reason lies in the effect of muzzle blast on projectile stability. Carlucci pages 163 to 165

High efficiency loads are those loaded with slow propellants where the barrel pressure is high relative to chamber and position of burnt is close to muzzle.

The muzzle blast is bigger than than that of the low efficiency load ( ie fast powder) where the blast is smaller.

Corner page 142 and on expands on this.

The bullet may have the same muzzle velocity but the initial disturbance on stability is larger for the high efficiency load hence then a larger initial drag effect until disturbances are damped out.

quote:

Originally posted by ALF:
The bullet may have the same muzzle velocity but the initial disturbance on stability is larger for the high efficiency load hence then a larger initial drag effect until disturbances are damped out.

The moon has a significant gravitational pull. It is so powerful it is the primary force responsible for changes in tides.

With that in mind, consider that a bullet fired directly toward the moon on the horizon will decelerate at a slower rate than the same bullet fired from the same rifle in the exact opposite direction and away from the moon. The first bullet has the gravitational pull of the moon working against the drag. The second bullet has the gravitational pull of the moon working with the drag. Time of flight and resulting impact elevations will vary accordingly.

Now, for both the example I cited and your example of differences in "initial drag effect" caused by "initial disturbance on stability":

I challenge you to

A. Measure those velocity differences in typical sporting cartridges using COTS chronometers designed for shooters and hunters.
B. Discern or even measure any differences in point of impact on a target placed anywhere from 50 yards to 1000 yards, again using typical sporting ammunition and consumer grade measuring tools.

Both examples describe theoretical minutia with absolutely no meaningful effect in the ordinary world.

We might as well discuss the differences in Coriolis effect on bullets fired in different directions at different latitudes and in different hemispheres.

Luke "May the FORCE be with you"

Grenadier:

It amazes me that you can claim that the "minutia" as you call it has no effect on what we do as shooters and reloaders.

Have we dummied the process down so much that we dare not ask why and how ?

We are dealing with a physical event or chain of events that can divided up into a magnitude of sequential minutiae. Each small and unmeasurable and yet without each the event cannot take place.

The magnitude of forces and the very short duration of the internal ballistics cycle makes much of the events minutia as you call it unmeasurable !

However having said that we have a 150 odd years of gunnery science that has carefully and diligently mapped out the process to the point where today the arms industry can design and build from scratch a gun system with all the ballistics and engineering paramaters known without firing a single shot !

If muzzle blast disturbances were not important why do we pay so much attention to barrel crown design and integrity. Why are we concerned with projectile concentricity and neck tension in barrel ? It all comes down to this pesky little thing called drag !

next thing, you are going to tell us the Coriolis Effect is statistically insignificant.

For years the worlds foremost wound ballisticians have considered and pontificated on the subject of wounds and bullet yaw in close up shots.

Up to 1994 there was not a single study published in the English literature actually investigating this phenomenon.

the reason for this possibly because the conventional lab set ups to study flight characteristics of bullets in aerodynamic labs have the gun set up in a blast chamber shielding the measuring instruments from muzzle blast.

This means that the first point of measurement and spark photography is set up some distance from the gun muzzle. So the bullet yaw has already started damping out and it was widely accepted that the yaw angle some feet from the muzzle was about 2 to 3 deg.

Knudsen and Sorenson in 1914 published the first known study ever looking at small arms bullets fired from common military arms where yaw angle at muzzle egress was actually measured.

as drag is a function of yaw angle and drag is a important determinant in wound production this study proves why some close up wounds can be so devastating.

quote:

Originally posted by ALF:
If muzzle blast disturbances were not important why do we pay so much attention to barrel crown design and integrity.

The simple fact is that we don't. ALF, you just helped make my point.

If I went through some mathematical juju to adjust and ream the muzzle crown to every load my 27" barreled single shot rifle would soon become a 2" barreled single shot pistol.

If we had the required test and manufacturing equipment, along with the technical know-how, we could design an optimized crown specifically for a particular bullet, loaded to a particular velocity, with a particular powder, in a particular rifle barrel, for a specified air temperature and density. But not only is that impracticable, it is a ridiculous concept. That's why the shooting industry has settled on a handful of crown designs that are used for the full gamut of cartridges we shoot.

Again, this is theoretical science and minutia far beyond any practicable application in the ordinary world.

Back to the OP question and your explanation of a velocity difference as a result of "initial drag effect" caused by "initial disturbance on stability", I say that you cannot:

A. Measure those velocity differences in typical sporting cartridges using COTS chronometers designed for shooters and hunters.
B. Discern or even measure any differences in point of impact on a target placed anywhere from 50 yards to 1000 yards, again using typical sporting ammunition and consumer grade measuring tools.

In other words, your theoretical discussion, as interesting as it might be, is moot with regard to the OPs simple, ordinary world, question.

Grenadier:
Whatever rocks your boat !

I simply gave some input on the question of fast vs slow powders and their effects. No more no less ! ( and it is not opinion , its defensible science )

Whether we acknowledge it or not, whether we ponder it or not every time a trigger is pulled on a loaded round a physical event takes place. The force magnitude, time fraction and temperature change so large and so fast it defies simple accurate measurement. So all we are left with is applied theory !

Whether you or I or the commercial munitions industry pays any attention or value to this bothers me not.

If if they do not ( and I strongly doubt it ) then they are ignoring the fundamental principles of how our guns and the powder they sell and manufacture works.

quote:

Originally posted by Pegleg:
If a guy loads some cartridges with everything being the same except the powder and charges, will cartridges loaded with a fast powder and cartridges loaded with a slow powder that have the same MV (2700 fps)have the same downrange ballistics?

If you would like an answer that is "acceptable within a statistical margin of error to ballisticians who have been developing data and earning their title as ballisticians in laboratories with ballistic equipment for decades", then your answer is yes! However, if you want the Accurate Reloading elite/persnikity version on a technical level within a gnats arse that may not even be measurable, then your answer is "Every time we weigh a load, measure a shots velocity, every time we pull a trigger on a load we have to cognizant of the fact that "The Universe is Stochastic and Non linear"..

Hope that helps.

Elf I for one enjoy your style and academic approach.It certainly inspires a spirited exchange of diverse understanding.

roger

quote:

Originally posted by bartsche:
Elf I for one enjoy your style and academic approach.It certainly inspires a spirited exchange of diverse understanding.

roger

I do to. The man is clearly on another plateau of comprehension than a simple man like me.

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I do to. The man is clearly on another plateau of comprehension than a simple man like me.

I'm to old think I'll stay uniformed (uninformed) .

quote:

Originally posted by ramrod340:

quote:

I do to. The man is clearly on another plateau of comprehension than a simple man like me.

I'm to old think I'll stay uniformed.

That's too bad. Your punchigrachkon could stand a little work.

quote:

That's too bad. Your punchigrachkon could stand a little work.

Never claimed to know punchigrachkon much less spellin.

Thank god for the ability to edit, my fingers out run my brain and when I go back an reread my posts it often scares the $hit of me.

I know what you mean..