I am a little miffed at my measured velocity differences during my load development phase.
I have sorted all my cases (R-P brass),I have 24 3x reloaded brass. All weight within a half gn of each other.
I have sorted my accubonds so they are all the same weight exactly.
Tumbled, then ultrasonic cleaned prior to loading.
All brass sized to exactly the same dimensions. with the exception a some slight variance in case neck length.+/- .001.
This batch of cases was annealed prior to this loading.
I have each charge measured exactly.
Used rcbs charge master for all weight measurements and powder throwing.
This batch of cases was annealed prior to this loading.
Primer pockets all uniformed.
I got my best group with 74gn H4831sc measure at 2960, 3011, 2932.
3 in the x, perfect clover leaf (.4x in.)

How can i get this group with the variation in measured velocity, what can i change in my procedure to tighten this up some. bullet seated .010 off the lands.

I am scratching my head here?

You could try sorting the powder flakes by weight. Sorry, that was mean.

I've been handloading for 50 years, 25 of those seriously. There are many others on this forum with more knowledge, but I did take a couple of quarters of statistics in grad school.

How much variance is bad? At what point does it result in poor grouping? It could be that the BR bughole shooters are getting similar variance. How much bullet drop results from x fps? Your total velocity spread is abou 2.5% of average V. Considerin all of the variable, that doesn't seem like much. For example, the barrel condition varies shot-to-shot. Also, it is a common observation that loads with a fair amount of V variance often produce excellent groups.

My suggestion: Stop wearing out your hair.

Are you neck sizing, or full length sizing?
Did you turn your necks?
Is it the loads, or the rifle, what are you shooting them in?

Are you sure your chronograph is giving you correct/accurate numbers?

i'm going back 25 year or so when i first got a chronograph. Always was curious about weighed vs measured powders. Anyway i loaded 5 rounds each in a half a dozen calibers, each set was weighed stick, weighed ball, measured stick, and measured ball. My results were that the most velocity difference was in weighed stick, then weighed ball, then measured stick and last measured ball. In no case the the velocity differences make much of a difference in group size.
In any case it sounds like you're loading 375 and a .4 group should certainly kill anything you shoot with that round.

Three shots really tell you little. Except in this case that the rifle appears to be sighted-in.
I know this doesn't answer your question but I've never been that excited by small variations like that. And when you look at the percentage of your total velocity the deviation is, it's rather small.
Some folks thrive on small spreads and such. My primary goal is accuracy and then velocity. It appears that you have both the accuracy and velocity so I would be inclined to say "it is what it is" and go hunting or shooting.

quote:

How can i get this group with the variation in measured velocity, what can i change in my procedure to tighten this up some. bullet seated .010 off the lands.

The answer to the first part of your question is easy, small variations in velocity don't really matter when shooting at a fixed range.

The second part will be a little more complicated and it mostly depends on what your rifle, loading equipment, cartridge components and shooting technique are capable of doing, or not doing. Some of the things mentioned might help, others might not, but the first question is will your technique/skill be able to show any improvement in your ammunition? I've loaded accuracy rounds for guys that couldn't shoot them well enough to even mess with laoding them.

What cartridge?

What bullet?

What rifle?

The load may not be compatable with the componants.

What chronograph?

What distance to the start screen from the muzzle?

Additionally, a 3 shot group/test is not a good sample. A 7 shot test is minimum to give 90% assurance the data is valid.

Larry Gibson

Try lee crimp.

Ahhh, those nasty little secrets those cronos expose...

quote:

Try lee crimp.

Could be. I went through the same procedure recently with my rifle (actually did not weigh cases or bullets) and trickled each load.

My 11 shots were: 2511, 2511, 2497, 2505, 2517, 2517, 2498, 2498, 2515, 2522, 2526.

Baxter makes a good point. The Lee crimp will give you a more uniform bullet pull. Something that may be lacking due to an inconsistant annealing between cases.

Lee factory crimps do not make more uniform crimps, they only increase bullet pull. Any variance that will affect the uniformity from one round to the next will still be present. They might show a decrease in the extreme spread of a group by making the powder burn more completely and uniformly but this could also be fixed by choosing a powder that is more tolerant for the load.

If consistant velocities are the goal, then you need to choose the most consistant primers you can find. But for most practicle purposes, other than varmint hunting loads, chronographs are better left at home.

quote:

This batch of cases was annealed prior to this loading.

Getting an even and consistent annealing is very difficult without precision equipment. Not having any other information about the caliber, bullet weight, primer, etc., I would first investigate the annealing process as introducing an unknown variable.

There is no reason to leave a chronograph at home, you just have to understand their proper place. Some loaders just haven't yet figured out what they need to worry about, and don't need to worry about.

Since I don't know GSP man, or they type of shooting he does, I"m not going to judge him, or his chronograph, or what he should, or should not be doing with the information.

At a 100 yards, 100 fps spread is no big deal.
At a 1000 it's a little different.

Hopefully he will return to answer some of the questions that have been asked so we are all in a better position to help him.

After you have a good scale and, perhaps, a tumbler, I think the next "nice to have" item on your purchase list is a Chrony. Properly used, it can tell you a great deal more than how fast your bullets are going.

quote:

Properly used, it can tell you a great deal more than how fast your bullets are going.

Such as...?

Oh, used with a good load book(s) it can tell you your approx pressure. It can tell you that adding more powder is pointless. One case I bring to mind was a 22-250 varmint rifle of mine. Each spring I would re-set the COL because of throat erosion. I would then add powder until my velocity was where it had been. I could then take the rifle shooting and the POI was the same. Before I had the rifle rebarreled, my powder charge was out of the book but I still considered it safe because my velocity was well under what the book had as max. By the same token, if your velocity is running high compared to a good load book(s, you can be assured that your pressure is running high also. If the load books tell you that 50grs of xyz should give you 2800fps and you acchieve that with only 46grs, it'd be a good idea to stop there.
As the load books tell you, their info is generic. A chrony can help you tailor the loads to your rifle.

quote:

I got my best group with 74gn H4831sc measure at 2960, 3011, 2932.
3 in the x, perfect clover leaf (.4x in.)

Nice group .4" for a 3 shot group is not bad at all. From the load is sounds like a 300 Winmag or close to it, it would be hard to cram that much powder in a .17 Rem Mag . If so, they can produce some great accuracy and it sounds like you are there.

When I use my chronograph and start seeing a diminishing return for the additional amount of powder, I start looking for the most accurate load in that area and call it good for the purpose of that caliber.

There was an article in Hodgdon #26 that gave some advantages to using a chronograph, and guessing pressure was part of it. What they don't tell you is that the author was a chronograph salesman.

The problem is that a chronograph does not tell you anything about the peak pressure you are getting, only the average. Peak pressure and velocity have no relationship, and there is no way to translate one into the other. A small increase in velocity, even 10-15 fps, has been noted in loads creating an increase of over 9,000 ft/lbs of pressure. It is also possible that the increase in peak pressure is indicated by a loss of velocity, which to a person using a chronograph as a guide is an invitation to add more powder.

Loading manuals are only a generic guide, and they almost all tell you that. There are many things that can affect the velocity and pressure that you are getting compared to what they are getting and if you look at their manuals over the years they get different results every time they test an identical load on the same equipment. There is only one way to tell you what peak pressure you are getting and that is with a pressure gauge.

The problem lies not with the chronograph, the problem lies with the modern shooter who absolutely refuses to learn how internal combustion drives a bullet to a certain velocity.

There is this constant insistance that somehow pressure and velocity are not related when in fact it is this very relationship that defines the modern gun.

The relationship however is more complex than simply a statement that claims that X amount of pressure gives Y amount of velocity.

The holy grail of the classic ballistics problem was two fold, firstly the solve the velocity equation and secondly to accurately determine the pressure needed to produce that certain velocity.

The achievements in the solving of these two essential elements of the problem have made men famous. Benjamin Robins the father of modern gunnery for his contribution in the form of the chronograph and Alfred Nobel ( as in the Nobel Prize) for the mathematical depiction of the pressure / time curve that bears his name.

Perhaps we could argue that it was these two inventions that have caused modern shooters no longer to consider how and why guns work and ulitimately their state of denial as to the relationship between pressure and velocity.

That was what gunnery is all about. No more no less

( also a historical fact that gunnery officers of yesteryear were in fact learned men, who commanded respect from common men by virtue of their learned status. A Status that was hard earned and for which title was bestowed that was kept even after retirement from active service. Hence then also the notion that they, the offiicers did not carry arms, were relatively safe from being shot at by enlisted men of the enemy and were afforded privilige even in capture)

How strong does the gun need to be to harness the pressure generated by internal combustion to drive a projectile of specific sectional density to a desired known velocity, which would assure that that projectile strikes a target a certain distance away with accuracy and precision that in essence is what we are dealding with every time we pick up a modern gun and shoot it. Perhaps modern production practice has made it so easy to use that we do not have to think of how it works or came about. Even if we wish not dwel upon the why and wherefore of the physics that underlie the action of shooting it does not mean it is not happening each time a gun is shot

Every time the hammer is brought down on the primer loaded in a charged case the same sequence of physical events go down which envolves pressure and ultimately velocity...... the very same people who deny the pressure velocity relationship and why chronographs are in fact useful in reloading proably also deny that Sectional density is a factor in ballistics.

quote:

Originally posted by Squib:
There was an article in Hodgdon #26 that gave some advantages to using a chronograph, and guessing pressure was part of it. What they don't tell you is that the author was a chronograph salesman.

The problem is that a chronograph does not tell you anything about the peak pressure you are getting, only the average. Peak pressure and velocity have no relationship, and there is no way to translate one into the other. A small increase in velocity, even 10-15 fps, has been noted in loads creating an increase of over 9,000 ft/lbs of pressure. It is also possible that the increase in peak pressure is indicated by a loss of velocity, which to a person using a chronograph as a guide is an invitation to add more powder.

Loading manuals are only a generic guide, and they almost all tell you that. There are many things that can affect the velocity and pressure that you are getting compared to what they are getting and if you look at their manuals over the years they get different results every time they test an identical load on the same equipment. There is only one way to tell you what peak pressure you are getting and that is with a pressure gauge.

On a whole, I think I'd rather take the word of a professional that has a liability for his published statements than some babblespeak I read in cyberspace. (depending, of course, on who's doing the babblespeak )
I don't feel the need to run out and buy several thousands of dollars worth of pressure testing equipment any more than I feel the need to be a master mechanic to change the spark plugs in my truck or drive it to the store. That work is already taken care of for me when I buy a load book. The load book doesn't extrapolate the pressure curve for me. But it does tell me how much pressure and velocity I should be getting when I load xxx powder behind a xxx bullet. With the load book and a chrony, I can load accurate ammo with peak performance for my rifle.
The chrony is a tool. How you use it and how well you use it is kinda up to you. If you think it's superfulous, then don't buy one nor use one but don't depreciate it's value to those of us that know better.
FWIW, when Rem/Win/Fed orders a couple of tons of powder and it arrives. The guys in the white coats take samples and determine its burn rate. From that, they extrapolate pressure and from that they extrapolate how much is needed to achieve a certain velocity. That kinda denies that there is no relationship between pressure and velocity don't you think? Or is Rem/Win/Fed doing it all wrong?

First of all there is a big difference between the average pressure of a load and the peak pressure of the same load. (This is according to those old guys that didn't have to carry arms.) Two different loads might have the same average pressure, but one will blow the gun to pieces while the other will be perfectly safe.

I don't own thoushands of dollars worth of pressure testing equipment either, I use load data from the same load manuals everyone else here does and rely on their pressure equipment. I do know that the data they give is an average of the velocities and an average of the peak pressures that their test loads gave, but due to differences in their test equipment and my firearms, and differences in various other aspects from their shooting to mine, that I will not get the same results, I might get better or I might get worse, but, like those old gunny men, I don't follow modern trends in trying to blow my guns up trying to make them do something they wern't made to do. I also don't rely on a chronograph to give me information about something it can't do.

By the way, if you read the fine print the professional chronograph salesman is not liable for his words, nor is the manual it was published in. As for babblespeak, wether anyone believes mine or yours makes no difference to me. I've been on several reloading forums and anyone that doesn't double check what they read on the internet through a reliable source is making a big mistake.

A chronograph has no capability of doing anything other than telling you the velocity of a projectile (as calculated by the time of flight interval between two fixed points).

An experienced reloader can use the relative velocities of identical loads to determine velocity consistency and potential accuracy. An experienced reloader can also, in combination with relative pressure indicators, known gun attributes like barrel length, and known data from second-party sources, make reasonable inferences about relative pressures and the performance of one load versus another.

So yes, all a chronograph can tell you, by definition, is velocity. What you are able to do with that limited information in combination with other knowledge extends well beyond simply knowing velocity.

Well squib, if you set out to totally confuse me, you've done a fine job. When I read my load book and it tells me that a certain load generates a certain pressure, I assume that pressure figure is an average of several cartridges being fired. I further assume that the pressure figure given is the highest figure achieved during ignition of the cartridge. It is not the "average" of the pressure from the striking of the primer until the bullet exits. Correct me if I'm wrong.
I don't quite understand how you are using the word average with regards to pressure. And I don't understand how it would be used for reloading. Also explain to me about the wreaking of a gun.

quote:

Originally posted by Squib:
Two different loads might have the same average pressure, but one will blow the gun to pieces while the other will be perfectly safe.

Please explain how this will and/or can happen.

Obviously some real misconception abound regards to pressures; what pressures really are, what pressures really do, how pressures are actually measured and what the MAP, MPLM and MPSM actually mean.

Larry Gibson

quote:

An experienced reloader can use the relative velocities of identical loads to determine velocity consistency and potential accuracy. An experienced reloader can also, in combination with relative pressure indicators, known gun attributes like barrel length, and known data from second-party sources, make reasonable inferences about relative pressures and the performance of one load versus another.

So yes, all a chronograph can tell you, by definition, is velocity. What you are able to do with that limited information in combination with other knowledge extends well beyond simply knowing velocity.

Technically you are right, but the problem comes with the known data from secondary sources. I have never seen any loading manual give all the information that you would need to make a comparison from their test equipment to the reloaders firearm(s). Differences in chamber, throat and barrel dimensions, ambient temperature, temperature of the ammunition when fired, relative humidity, humidity content of the powder, lot to lot variation in every component, and several other factors all will affect pressure and velocity variances. The only thing the pressure and velocity figures are good for in the manuals are to give the reloader an idea of how the various loads compared in the test firearms. Many of them do not give pressure data for the simple reason that reloaders want to use them for the wrong purposes.

quote:

Originally posted by wasbeeman:
Well squib, if you set out to totally confuse me, you've done a fine job. When I read my load book and it tells me that a certain load generates a certain pressure, I assume that pressure figure is an average of several cartridges being fired. I further assume that the pressure figure given is the highest figure achieved during ignition of the cartridge. It is not the "average" of the pressure from the striking of the primer until the bullet exits. Correct me if I'm wrong.
I don't quite understand how you are using the word average with regards to pressure. And I don't understand how it would be used for reloading. Also explain to me about the wreaking of a gun.

I think the confusing part here is the English language, and my lack of understanding of it.

"Average" can be used in different ways and I don't know a better way to say it.

The pressures listed in manuals are as you think, an average of the highest pressures registered on the test medium.

The average pressure of the load, which is my definition, is the combination of the amount and duration of the pressure curve.

The "wrecking of a gun" is a little harder for me to explain. A powder that burns very fast can cause a very high amount of pressure for a very short time, while a powder that burns slower will not get as much pressure all at once, but over a longer period of time will generate about an equal amount. So even though they both give the same amount of pressure, the rapidity in which the first one acts can generate enough pressure to damage the gun.

Squib, as I understand it, your agrugment is essentially that since chronographs cannot provide perfect information, they should not be used. In logic, this is a error, known as the Utopina Fallacy. Just because something in not perfect, doesn't mean it is not useful.

The Chronograph is one of the most economical ways a handloader can gain additional information about his loads. I've had loads chronograph 400 fps different then published. In these instances, it doesn't take $10,000 worth of pressure testing equimpent to know something is not going as expected, and a different approach may be in order.

Blowing up guns? Who here said anything about blowing up guns? Who said anything about being a raw speed demon? The suggestion have been to use an economical tool to gain additional informatin, and then make reasonable adjustments based on that information.

If you would take the time to read vapordogs posts carefully, you will notice he's not advocating anything irresponsible, or unreasonable. Modest powder increases to offset throat errotion to mainatian velocity and accuracy sounds very reasonable (and cleaver) to me.

In addition, I don't see where anything you've said has been useful to the OP (origianl poster). Telling him to throw away his chronograph, unless he's also going to invest in 10K of new pressure testing equipment, is not exactly a constructive answer. If you have access to this kind of equipement, perhaps you would like to test loads of some of us and post the results for everyone. Of couse in a Utopina world, that would still defeat the purpose, because the results would be in your test equipment, and not in our rifles....

Antelope Sniper, It seems you've missed it altoghether, I never said anything about perfection, needing $10,000 worth of equipment, that anyone should throw anything away or etc.

Instead of going on with this dead end dribble, especially since it appears the OP hasn't been back since his OP, I won't waste anymore time with it.

Thank you.

quote:

Originally posted by Larry Gibson:
Obviously some real misconceptions abound regards to pressures; what pressures really are, what pressures really do, how pressures are actually measured and what the MAP, MPLM and MPSM actually mean [ COLOR:RED]in relation to the velocities actually achieved[/COLOR].

Larry Gibson

In this instance I believe Larry has nailed it with a minimum possible number of words.

quote:

Originally posted by gspman1:
I got my best group with 74gn H4831sc measure at 2960, 3011, 2932.
3 in the x, perfect clover leaf (.4x in.)

How can i get this group with the variation in measured velocity, what can i change in my procedure to tighten this up some. bullet seated .010 off the lands.

I am scratching my head here?

All of the variables you mentioned; good work, however there are some many add'l variables that we don't usually consider-

chronograph capability (they have variations too-my chrono says 5% or better accuracy, 5% of 3000 is 150fps

scale, probably stated as +/- .1 grain, so a variation of .2 grn on average...

bullet weight, bearing surface, shape (they may "look" sexactly alike, but they are not!)

Barrel temp/expansion rate


Gosh, a mentor was even starting to talk about earth's rotation at 600 yards let alone wind retardation caused drop/rise based on a direction and value....

I actualy think shooting and reloading is part science, part magic!

As to the original posting:

Variance in velocities measured.

Ballistics per se is stochastic in that there is a inherent randomness to every step of the process, whether it be the events themselves or the measument of those events.

The same gun, same componets, loaded to the same precision ( or not) will give a variance in data.

Understanding this key to the interpretation of data.

As to the use of the chronograph and it's usefullness.

Because of certain physical relationships in internal ballistics process it is possible and practical to use velocity data to aid in decision making regarding safe pressure limits.

Simple applications such as "Barsness's rule of thumb" (which incidently is not his, just erroneously ascribed to him by the US shooting press) is an example of simple application of principle.

The use of the V/C curve another application as outlined by Johan Laubscher formerly of Somchem in the old Somchem load manual ( now working in the US as a ballistician . )

This principle is used by CIP when proofing ammunition submitted for guns for which they have no pressure barrels. The validity of the method is outlined in their manuals and accepted as a matter of law.

The application is simple, measure velocity of the bullet of which SD is known, calculate muzzle energy and now you have the answer to a formula for which other variables are known such a volume dimensions of barrel and chamber, amount and physical values the propellants, load densities and you have a appproximation of the mean barrel presssure that produced that velocity.

Homer Powley put this into a slide rule, all of the current computer based load programs are a direct application of this principle.

Interpretation of the data and validity produced however require some knowledge of how the values are derived and how they compare to real data gained from the shooting of a individual gun. ie where does the calccualtion overestimate or underestimate and why.

The same principles have been used for more than a century now by those who design and build guns of war.

It is possible to design and build guns and munitions to specific ballistic spec without every firing the gun..... Same principle used to design a rocket or car enjin to deliver a certain performance without actually having one to test.

Modern refined computer based programs have replaced the older crude versions of the application. Their accuracy now perfected to a point where ballistic performance can accurately be predicted without firing a single round or rocket.

wow... this post really took off since i last checked back, some very good points to ponder by all.
1st and formost i am developing this load primarily for elk hunting this fall. I believe i have it. My original question was how was it that i was getting such good grouping (for me) with what i considered a large velocity variation.
i have been able to repeat this grouping trend but my velocity variation has improved.
Here is what i did. I took my neck cleaning brush and wrapped a bit of 000 steel wool around and polished the inside of my necks.
Now I am showing variation of +/- 16fps on a 5 shot strings my last outing to the range.
I moved out to 200 yds (my zero for this rifle)
and am currently grouping .9xx"...I am cool with that for sure.
I was wondering if neck tension was causing my perceived issue. Not sure if the polishing is actually the ticket, but i am inclined to think that it has something to do with it.
Still playing with seating depth a bit, but that will be my next trip to the range.

300 wm
180gn accubond
federal mag primers
rcbs fl sizing die
innovative tech. collet resizing die
rcbs chargemaster dispenser/scale
chrony alpha master 12ft from muzzle

quote:

Originally posted by wasbeeman:

quote:

Originally posted by Squib:
There was an article in Hodgdon #26 that gave some advantages to using a chronograph, and guessing pressure was part of it. What they don't tell you is that the author was a chronograph salesman.

The problem is that a chronograph does not tell you anything about the peak pressure you are getting, only the average. Peak pressure and velocity have no relationship, and there is no way to translate one into the other. A small increase in velocity, even 10-15 fps, has been noted in loads creating an increase of over 9,000 ft/lbs of pressure. It is also possible that the increase in peak pressure is indicated by a loss of velocity, which to a person using a chronograph as a guide is an invitation to add more powder.

Loading manuals are only a generic guide, and they almost all tell you that. There are many things that can affect the velocity and pressure that you are getting compared to what they are getting and if you look at their manuals over the years they get different results every time they test an identical load on the same equipment. There is only one way to tell you what peak pressure you are getting and that is with a pressure gauge.

On a whole, I think I'd rather take the word of a professional that has a liability for his published statements than some babblespeak I read in cyberspace. (depending, of course, on who's doing the babblespeak )
I don't feel the need to run out and buy several thousands of dollars worth of pressure testing equipment any more than I feel the need to be a master mechanic to change the spark plugs in my truck or drive it to the store. That work is already taken care of for me when I buy a load book. The load book doesn't extrapolate the pressure curve for me. But it does tell me how much pressure and velocity I should be getting when I load xxx powder behind a xxx bullet. With the load book and a chrony, I can load accurate ammo with peak performance for my rifle.
The chrony is a tool. How you use it and how well you use it is kinda up to you. If you think it's superfulous, then don't buy one nor use one but don't depreciate it's value to those of us that know better.
FWIW, when Rem/Win/Fed orders a couple of tons of powder and it arrives. The guys in the white coats take samples and determine its burn rate. From that, they extrapolate pressure and from that they extrapolate how much is needed to achieve a certain velocity. That kinda denies that there is no relationship between pressure and velocity don't you think? Or is Rem/Win/Fed doing it all wrong?

There is not a linear curve as it relates to pressure and velocity and esp when you get towards the upper end it gets ugly very fast. The manuals are only a guide—as you well know sometimes a load that was fine in a manual will show pressure signs when used in your individual rifle.