Typically, resized brass has slightly more capacity than factory new brass. This is especially true if the brass is neck-sized or the shoulder is preserved for the specific rifle chamber.

My question concerns velocity differences and powder charge differences between new brass and resized brass.

What have you all experienced with calibers around 45-50 grain charges, 70 grain charges, and 90 grain charges?

How much of a difference does the new brass make?

Do you try to accommodate the difference with 1/2 or 1 grain of powder?

Thanks. I like to learn from a pool of experience where I can.

Nothing!

expect 1% difference .. if it's a hyper sensitive barrel harmonic, it could be a move in POI .. in terms of where it hits when hunting? meh, at most, in a decent rifle, an inch

It mostly depends on the actual size of the chamber verses the actual size of the new brass. Both chamber specs and brass specs have tolerance ranges, and a chamber at minimum specs paired with brass on the upper end of the range will show less velocity/pressure difference than will the opposite. Regardless any change will be minimal; like Saeed I make no accommodation for new or used brass.


.

Seen a gov test on 5.56mm, new vs fired. Volume was 4% larger on fired.

Other wise, no ideas.

I'm with Saeed on this - nothing !
My experience mostly with charges from high 50 gns to high 60 gns.
If new brass is not resized ( to uniform neck diameter ) prior to first loading initial results can be more erratic but that's about the only cause of any difference I've experienced. My preference is not to shoot new, reloaded, brass for hunting use. I shoot any / all new brass once then start using the reloads for hunting.

quote:

Originally posted by TX Nimrod:
It mostly depends on the actual size of the chamber verses the actual size of the new brass. Both chamber specs and brass specs have tolerance ranges, and a chamber at minimum specs paired with brass on the upper end of the range will show less velocity/pressure difference than will the opposite. Regardless any change will be minimal; like Saeed I make no accommodation for new or used brass.

I agree 100% with TX Nimrod above and Quickload tells you to measure your case capacity with a fired case.

And there will be far less difference with a full length resized case than a neck sized case.

The good news is the larger the case capacity the less effect on velocity and chamber pressure.

Example, I have a standard lee full length .223 die that reduces the case diameter more than my RCBS small base die.

But the difference in the actual case capacity of a .223 case at 30.6 and a .223 case at 28.0 can cause 5,000 psi difference in chamber pressure with the same powder charge.

In a tight chambered rifle, like my 1000 yd BR gun, there was no difference between new and fired brass in terms of velocity. With a typical slightly tighter custom hunting rifle chamber, I have seen velocity increase a little. I assume that’s because the energy lost to expand the case to the chamber is a bigger factor than a small increase in capacity. In a typicaly chambered factory rifle, it’s completely random. Sometimes there is no change, sometimes more, sometimes less. I think a straight walled case would change the least and a belted bottle neck change more, but who knows? Regardless, all the changes I have seen have been small, like 1%—which we could argue is just normal variation......

Man, oh man. It's gonna be a looong winter.
How are you determining that a 2.6 gr increase in powder is generating 5K difference in chamber pressure?
I shoot fire formed brass for greater accuracy not for greater powder capacity.

Just my opinion. The chamber dimension controls the pressure. The case will expand to fill the chamber. Take a thin case and thick fired in the same chamber you will get a higher pressure because the net volume is less. If you toss in the capacity difference in QL yes it will calculate higher pressure because you have in fact told it you have a smaller chamber.

QL uses a fired case to simply determine the net chamber capacity of your chamber and your brass. Fired brass might be more accurate because it improves the alignment.

I've loaded my own blown out 280 case wildcat. Using the same load of med burn rate powder before and after expanding the case volume about 10% resulted in not enough POI change to worry about.

Again my opinion

Basically...DEPENDS...everyone gave excellent answers right on point.

If your rifle is a commercially made hunting rifle with a chamber that is all over the place...MAYBE..the only way to know for certain is to water weigh a case, then fire it and water weigh it again and compare the results

The same thing goes for a tight chambered ultra target rifle...THERE IS NO SUCH THING as equality here and you have to get VERY accurate and PRECISE which isn't going to happen in a commercially built rifle...for the most part, nitpicking aside.

There, USUALLY, is variation between brands of brass..I've been working with my Lapua lately and MY Norma brass weighs in a 116 gr H2O fired...my notes say Hornady was 116 gr unfired and 117 gr fired and Lapua was 114 gr fired...QL listed 108 gr didn't say which and I've seen listings from 106 to 120, that's ~12% difference which WILL make a difference in velo and pressure even in a very sloppy chamber.hunting rifle....so you have to weigh YOUR OWN RIFLE'S CHAMBER and BRAND to know for sure. That measurement holds ONLY FOR THAT SPECIFIC CHAMBER AND BRAND...IT CANNOT BE TRANSFERRED WILLY NILLY.

I think this is the basis of many hoohaws on forums...misunderstanding and NOT UNDERSTANDING all the various nuances relating to reloading, velocity differences, pressure differences and so forth.

It also behooves you to fit your sizing die to your chamber or visa versa. Not only does this add life to your brass it also removes one of the areas that can cause inaccuracy...IF you match your case weight. I have 3 cases sitting on my desk that constantly remind me to "get'erdone".a 223 that was loaded and fired 50 times with a top load and is still OK to reload many more times...a 444 Marlin - 40 times and a 375 H&H thats gone 25 times and NO evidence of incipient head separation. I kept track of the trim amount doe ALL those cases but can't recall...each was different.

Keep reading and asking questions...even the hoohaws can provide good information in spite of the spitting and growling.

Good Hunting

quote:

My preference is not to shoot new, reloaded, brass for hunting use. I shoot any / all new brass once then start using the reloads for hunting.

Why do you not want new brass for hunting (assuming that you have uniformed neck diameter by a quick run through a sizing die)?

New or once fired cases for hunting...

Basically personal preference...a once fired case is SUPPOSED to fit the chamber closer and you could nitpick the fact of energy transfer/reduction in expanding the case, but, arguably, that can be chewed up and spit out IF YOUR SIZER doesn't fit your chamber...you might be reducing the case size even MORE than the original unfired case...HIGHLY ARGUMENTATIVE to say the least and doesn't really matter except to the literati, or is that the Illuminati???.

Personally, because I benchrest prep ALL my components...brass, chamber, bullets, rifles and because we have those wonderful bore scopes, and I mark my fired brass as to the number of times and have no need to hunt DG I just use whatever happens to be the next in line in a box. If I was hunting DG I would use once or twice fired just to POSSIBLY decrease any untoward probabilities.

Good Hunting

Ramrod is right; and of course, Saeed. Think about it; powder burning depends on chamber and bore volume, Right? And what do you think happens a millisecond after the powder ignites and pressures rise enough to expand the brass to fit the that chamber; at that exact point, all brass becomes the same size, whether new, fired, or sized. So that is going to result in the same chamber volume each time, anyway. As long as the bras is the same thickness.
Something to think about.

quote:

Originally posted by dpcd:
Ramrod is right; and of course, Saeed. Think about it; powder burning depends on chamber and bore volume, Right? And what do you think happens a millisecond after the powder ignites and pressures rise enough to expand the brass to fit the that chamber; at that exact point, all brass becomes the same size, whether new, fired, or sized. So that is going to result in the same chamber volume each time, anyway. As long as the bras is the same thickness.
Something to think about.

So--
Does the work involved in forming the case to the chamber subtract from the work that is transferred to the bullet?

Theoretically, yes, but how much? I think it varies from none, to, some.
For me, it makes zero practical difference.
Realize that I have done no testing on it, in any scientific way. Or any other way.

It does in theory and practice !

That is why firing solutions programs on big bore guns such as howitzers and ships cannon make allowances for expected bore wear after each shot. It is based on the principles of expansion volume and that the expansion volume incrementally changes after each shot.


Whilst our ballistics system is a micro version of the larger it is scalable and what applies to the larger applies to the lesser though on a lesser scale. It may not be evident in our limited ability to verify differences. They happen none the less.

With each firing and reforming our brass case flows and eventually we have to trim them to length which by necessity means a gradual loss of brass and a thinning of the wall. This de facto implies a change in chamberage.

The difference in "internal dimension of brass by manufacturer effect" evident for the same reason.

The Strain hardening effect after each firing of a case shown by he following.

We can all have opinions. Easiest is simply test your rifle(s) with new and formed cases. In a normal hunting rifle I'll bet you a you are worried about nothing.

You are about to cross the Atlantic in a one man sail boat.

And you are debating if you will actually cross over quicker going on out on a low tide or a high tide!

Good luck!

Ah Saeed ! I have a friend who years ago captained a racing yacht in the Cape to Rio Yacht race ! You will surprised at how much debate and pondering goes into choosing the course, tides , weather etc that little adventure ! In fact they have perfected it to a science !

I think we all should watch this thread VERY CLOSELY roger

quote:

Originally posted by ALF:
Ah Saeed ! I have a friend who years ago captained a racing yacht in the Cape to Rio Yacht race ! You will surprised at how much debate and pondering goes into choosing the course, tides , weather etc that little adventure ! In fact they have perfected it to a science !

And I have a friend who actually did cross the Atlantic in a small sail boat.

At least he and his friends claim they did.

I am not convinced, neither is his wife!

The gave us GPS coordinates, when they were supposed to be on route.

According to Google Earth, that put them in the middle of the Yucatan in Mexico!!

A few days later, they gave us another set.

And this time they were in the Western Desert in Libya!

And the only photos we saw were of them in a bar buying drinks and cheese!

quote:

So--
Does the work involved in forming the case to the chamber subtract from the work that is transferred to the bullet?

Well, if it did then that would mean that new brass would yield lower velocities than previously fired brass -- exactly the opposite of the premise of your question.

Its a bit like asking if the work done to a suppressor on the end of the barrel subtracts from the work done on the bullet. Of course not.

The pressure of the gas is determined by the volume of the pressure vessel. The volume of the pressure vessel has nothing to do with the relatively elastic brass case -- only the relatively inelastic steel chamber.

Now, you may indeed see a small but detectable difference in velocities between new and previously fired brass, but not because of how loose or tight the brass fits the chamber -- as has been said, the brass will fit the chamber perfectly and instantly once the round is fired. Any velocity difference (and it would be small) would be attributable to changes in neck tension and/or neck friction characteristics.

quote:

quote:

So--
Does the work involved in forming the case to the chamber subtract from the work that is transferred to the bullet?

Well, if it did then that would mean that new brass would yield lower velocities than previously fired brass -- exactly the opposite of the premise of your question.

Actually, I have heard people claim that very thing--that new brass will produce slightly less velocity. I tried to word the opening questions in an ambiguous manner to include the possibility that new brass was slower. When I've heard these claims it was usually at a magnitude of 50fps, that is 25-50fps slower, which may be a difference provided by 1/2 to 1 grain, depending on the overall load size. Presumably, so the claim, one can add 1/2 to 1 grain with new brass to overcome this if the load is not too compressed. On the other hand, fired brass might be slightly larger and need that half-grain to maintain pressure. So I've heard. That means that I've heard comments in both directions from old sourdoughs.

Myself? 25 fps needs pretty accurate testing and I can neither confirm nor contradict this from my own data. Temperature (both ambiant and barrel temperature) and the reliability of one's chronographs are factors. So I throw this out to the Peanut Gallery. It sounds like most people are like me, although from somewhere there is an idea that fired brass is preferable as closer to a specific chamber. Yet new brass rarely has a feeding problem.

Again, while on the question of brass for hunting--when trying to preserve shoulder lengths I sometimes have rounds that are tighter on closing a bolt. Necks getting fat? Not sufficiently resized? Compressed-load problem?? I typically retire brass on the sixth firing. (I put a permanent ink mark in a letter of the headstamp for each firing.) There is a balance between wanting the benefits of neck-sizing/partial-full-length-sizing and hunting rounds that need to feed flawlessly. Well, stuff that I load and take to Africa is new brass most of the time, run through a die to ensure that the necks are round and like previous loadings. Would this make a difference at 300+ yards? I can't say. Shots that far are rare in hunting situations and without benchrest control. I have learned little tricks over the years to help regularize things, like always putting a new round on top for a first shot rather than a round that has been bounced around in recoil.

The issue of work done to deform brass was brought up:

So from a thermodynamic point of view:

The ballistic (energy) efficiency of the gun is defined as the ratio of the kinetic energy of the bullet at muzzle to the total potential energy of the load ( charge + primer)

Simply put Eb = Ek (projectile) / Ep ( charge)

Given the fact that our ballistics system is a simple heat engine we see that its efficiency is actually very poor.

The best of the best only manages about 33 %!

The majority of small calibers do not even get there , they run in the twenty's

The point is energy is lost in the system as heat, sound, recoil energy, friction and energy necessary to deform the case and off course the temporary expansion of the chamber and barrel.

As kinetic energy is a function of the square of velocity it stands to reason that should energy be consumed in anything other than the task of actually accelerating our projectile to its egress velocity it is "lost" in the system.

The stress and strain behaviour of brass in terms of thermodynamics one such source of loss.

Of all the components utilized within the internal ballistics cycle the brass case likely the most imprecise part. Many studies have been conducted into brass as source of randomness.

A simple crude look at how imprecise brass is to weigh a batch of cases or even worse to see the differences dimensionally between brands. In the early editions of the American rifleman sporadic articles were published looking at the dimensional differences between brands even metallurgical studies into the ultra structure of brass cases.

Which of course brings us to the subject of the veracity of estimating pressure by measurement of the brass case by calliper after shooting

Now energy lost due to effects of brass quality may be small but it is lost none the less.

It has been said of our ballistics system that it is stochastic ( entirely subject to a degree of randomness)
This is off course very true and even crude measurement of a factor like velocity bears this out.

A string of shots fired from the same gun same components and loading to a high degree of precision we see that there is a variation in critical data such as velocity.

Precision in terms of our system is almost entirely a function of the manipulation of this randomness !

So now we enter the world of the rail gun where we no longer are dealing with a inefficient heat engine but a highly efficient linear electric motor ( 90% )

The very same reason why perhaps one we would ditch oor V8 Fords and Chevvies for Teslas

Alf,
I appreciate the description of themodynamics in firing a rifle, but it would help to get something on the degree of magnitude.

A ratio becomes helpful when there is a scale of magnitude for linkage. For example 2.5fps, 25fps and 250fps cover a hundred-fold spread. Is there any data on where on that scale brass deformation lands?

I take note that none of you have anything actually constructive to do with your time.
And you sucked me into reading all this; and writing this, thereby contributing to the waste of valuable resources, time being the most valuable of all.
I know, it's winter.

Put another way: Why bother with precision case prep at all ? If all of this minutia is waste of time then why bother at all ? we could all just shoot factory ammo and be done

Yeah...it's winter, it's cold, my shop is always ambient temp or lower/higher depending on the suns angle and hours of sunlight, it's muddy, it keeps on raining/snowing, days are short, I get SADs, my get up and go got up and went, I'm a total wuss at my age and HATE the snow/cold/darkness, I'm waiting for pieces and parts so I can do something constructive in a month or so...and factory ammo sucks for the most part...

How many of you have actually measured a box of factory ammo or took the time to break down each round and weigh the bullet, powder and measure the ogives??? I would hazard a guess and say, not many(it wastes time and I know the answer already, I've got better things to do, Yada, yada, yada) and it's good enough for most hunting situations so why bother with the rest...well ask a benchrester who would do ANYTHING AND MORE to win a match while smiling and patting you on the back...which to me is exactly the same thing as hunting only what you kill is a piece of paper.


AND...it STILL takes hands on and some kind of ACTUAL MEASUREMENTS, then some cogitating, to determine IF SOME question can be answered in a meaningful way, one way or another...a bunch of hot air and horse patoot, while ALWAYS interesting and informative, just doesn't cut it. Oh, Yes...I've done just that sort of testing and been doing it for a long time, so I do know some of the answers and they have lead to other very interesting observations and answers.

The fact that ES and SD will be masked most likely due to the small velo variations caused by all the other variations, shouldn't stop you from ACTUALLY testing out that theory empirically...you might learn something cool along the way.

Hey, DP...we need our time wasters and un-constructive activities otherwise there would be more "postal" activities and there are way to many of those already.

And, WHO is to say if the time is being wasted or not.

Good time wasting

quote:

Originally posted by ALF:
Put another way: Why bother with precision case prep at all ? If all of this minutia is waste of time then why bother at all ? we could all just shoot factory ammo and be done

sigh - just ,sigh

Some here say : go out and measure it ! or give us hard numbers !

The short and simple answer is you cannot , well not without the science or access to a ballistics lab !

The reason is you would want be measuring one variable in a chain of variables.

The problem would be to standardize on all the other variables and measure the effect of the case parameter(s) only.

What we do know is that the brass case is the single most important determinant of accuracy / precision in the internal ballistics chain ! and yet it is the one component made with the least amount of precision.

The reason for this is that other than the fact that the case is the seal which contains combustion the case determines the internal volume of the combustion chamber not the gun chamber itself second to this the case neck determines projectile alignment and tension as it enters the bore and finally case mechanical properties determines how shock is transmitted to the gun platform and ultimately how the platform will react.

When comparing a prepped case to a unprepped case, a fired case to a unfired or a multiple fired case would have profound effects of precision. Hence then the time spent by precision shooters and reloaders on the subject of the brass case.

The importance of the two graphs I posted cannot be emphasized enough !

quote:

Some here say : go out and measure it ! or give us hard numbers !

If you can't measure a difference caused by the case type because it is mixed with everything else why worry about it?

Case prep is an important part of accuracy but beyond a certain point, it becomes pointless. Busy work as it were.

For a hunting rifle the difference, if any, isn't enough to worry about.

Dave

As has been stated several times...if hunting accuracy is all you want at relatively short ranges, <500 yds, then mix and match will suffice...which has been proven time and time again.

If it's bugholes you want, and at 1000 yds plus ranges on relatively small targets then you better do the work and screw the non believers.

WHAT you want to do and HOW you can do it should be the guiding factors.

I can guarantee there are outliers in EVERY box of bullets, EVERY lot of brass, and EVERY box of primers...if you don't understand THAT then all the charts in the world won't mean squat. Mathematically it might show something very useful at some important point in the process, but if you don't get your hands dirty and blow off a few rounds, measure the he** out of everything in sight, understand some of the ballistic process AND understand that 2 gr difference in case volume can and will make a difference once you narrow the ES and SD, then all that math is just hot air...correct hot air, but hot air just the same...AND personal bias..which EVERYONE has toward what they like or dislike.

Anyone NOT doing the works can NEVER see the result of that tedious mind numbing number crunching because their targets are NOT small groups, they end up shotgun patters. YOU CAN'T SEE small variations in groups when the ES is 100 fs and the variation is 2 fs...plus it takes averaging MANY small groups then running a stat analysis to see something that small, but all it takes is a few wins for the value to be understood.

UNIFORMITY IS THE NAME OF THE GAME...just like in bowling, pool, sports and horse shoes...if you don't understand that then I have a few friends living in Vegas who would invite you to a few games of pool...FOR MONEY OF COURSE.

Probably 90% of the shooting word don't give a flying tada about any of this because they are supremely happy with what their rifles do AND DON'T WANT THE CONFUSION of understanding what they really don't know about the minutia...me included if some of my shooters do 5's 90% of the time by doing just a little bit of work when the snow is deep and I can't do much else...but I will do everything possible to be sure my long rangers shoot bugholes out as far as I can possibly shoot...I don't care if you think its folly or a waste of time or whatever...this is MY thing...go ahead and do YOUR thing and have a great time and enjoy.

Good Hunting

quote:

Actually, I have heard people claim that very thing--that new brass will produce slightly less velocity.

Again, the (minimal if any) difference in velocity yielded by new versus fired brass has nothing to do with its pre-fired dimensions, but can have to do with the varying qualities of the neck: The neck of fired brass where it contacts the bullet may be harder (or if annealed, softer) and its grip on the bullet or the surface friction between it and the bullet may differ from new brass. That might make a measurable difference in average velocity.