I really don't want to obsess on this. I really don't. But things just keep getting curiouser and curiouser.

I agree with you guys, when it comes to extreme spread, that it is not the end-all indicator of which load will shoot and which will not. I'm putting every load on paper and letting that tell the tale instead of the chrono. Period.

Now......here's what I ran into today. I shot a particular batch of loads that were well within acceptable pressure parameters. Here are the numbers for the string:

avg vel: 2933 fps
ext spr: 8.52 fps
std dev: 3.87 fps
group: 4.6"

How in the heck can a load that is so ridiculously uniform group so crappy???????

Harmonics baby, Harmonics!

Sometimes I think that the worst thing I ever did was get my cronograph. Befor my loads were traveling whatever I said they were and I had no idea what extream spred was. Now, like you, I can't figure out how such good loads can possibly be so bad!

I'm right there with you. Most of my rifles like a S.D. of 10-15.

JMHO and not based on any scientific fact;

I think that where standard deviation is important is when you find some really accurate loads at 100 yards, the one with the smaller SD will probably be the most consistent at 1,000 yards. I don't worry about SD in any load until I start thinking of shooting past 500 yards.

quote:

Harmonics baby, Harmonics!

Have as much if not more to do with accuracy that velocity spread.

Sounds like that load was just consistantly bad......... ............DJ

This is why Browning came out with the boss concept, and why Limbsaver technologies markets their little dampening device.

Yup

Harmonics baby, Harmonics.


Believe in them, defeat them and get the tight groups.

look at the gun rags and their load tests. some of the loads with the highest es's are the most accurate.

the opinions on harmonics are spot on. your rifle is telling you it doesn't like that powder/bullet combination or both.

Welcome to the fine art of tuning a rifle..
A chronograph is just a tool that tells us many things. It is not a means to an end, in this case tight groups. The only way to tune a rifle is sit down at the range and shoot.. the old fashioned way. Time and trial and error.
Like what has been said, its all about how and where the bullet exits the barrel on what part of the wave of vibrations, primary and secondary. And it doesn't make a hill of beans what the velocity spread is. If a barrel like a load, it likes it and the groups will indicate that. If it doesn't the groups will indicate that also. There is a whole lot more going on with internal ballistics than velocity spread.
You would do much better concerning yourself with things like,

bullet(try different ones)
powder charge(work out a spread in 0.5 grain increments)
primer(try different ones)
cartridge overall length..(shoot groups varying the length in .005" increments).. I have had more success in this area than all the above.

The moral of this story is, take what the chronograph tells you with a grain of salt.

The chronograph is the LAST part of the equation.. see what is accurate first...

Mininal Standard Deviation spreads do not equate to an accurate load always...

the chronograph should let you know the speed of your load once you developed an accurate load your rifle likes..

then the info should be used only so that you can set your scope for point blank range or within the parameters that you plan to hunt or shoot...nothing more of less...

that is kinda like expecting to soup up an engine for high horsepower and then expecting better gas mileage... it ain't gonna happen...

quote:

Originally posted by Strut10:
...I'm putting every load on paper and letting that tell the tale instead of the chrono. Period.

Hey Strut10, That appears to be a good start in the right mental direction. But you seem to be reluctant to let it sink-in very deep:

quote:

... I shot a particular batch of loads that were well within acceptable pressure parameters. ...How in the heck can a load that is so ridiculously uniform group so crappy???????

If you will go back and re-look at all the above responses, you will notice a trend in them toward Barrel Harmonics. And that is what I'd wager on myself.

When you are looking at the chronograph results, everything does seem nice. That consistancy is misleading you into thinking the groups should also be small. As was told to you by nearly everyone the last time, that just isn't necessarily how things work.

However, I don't remember anyone explaining "Why" it works out that way. You first need to clearly understand that when the chronograph shows low ES and low SD that it only means the Bullets are leaving the Barrel at close to the same Velocity. And that is all it means. Nothing complex about that - yet.

The problem is that the Barrel is probably in the mid-point of a Harmonic Oscillation. The reason that is important is because the "Tip-of-the-Muzzle" is moving at it's highest speed then. Therefore, ANY SLIGHT Velocity variation causes the Points-of-Impact to s-p-r-e-a-d out because of that Muzzle Movement.

When fired, a barrel is subjected to all kinds of pressure and stress - in multiple directions - simultaneously. It has a rotational stress "1"(due to the rifling), rotational stress "2"(around the centroid of the Butt Pad), as well as the normal radial stress imparted onto the Barrel as the Bullet travels up it's length, a lengthening(of the barrel) and shortening, etc, etc,. As the Bullet moves along, "some of these" work similar to an electronic Sign Wave where they expand, collapse, expand, collapse, etc., creating a Resonance.

To make things just a bit trickier, they start off at Zero, see a relatively low start, then a SUDDEN MAXIMUM Peak Pressure, and longer time variations during the duration of the Powder Burn - depending on the Cartridge Components and the Bore Condition.

Surely that cleared it up for you.

However, if there is still a bit of confusion, simply think of the Muzzle Tip moving in the shape of an elongated Figure " 8 ". And it will help in the long run to understand the Figure "8" movement can be skewed slightly left or right (depends on the Cartridge Components and the Bore Condition).

The trick to achieving the Best Possible Accuracy is to get all the Bullets in a specific Load exiting the Muzzle when it is at "either end" of the Figure "8" pattern. That is because the Muzzle Tip is slowing as it approached the Point of Apogee(or Perigee), nearly stops as it begins changing direction, and then begins speeding up as it heads for the other extreme. This is a Barrel Harmonic.

When you get the Bullets making an exit from the Muzzle when it has nearly stopped, you get the Best possible Accuracy. When you also have a low ES and a low SD(with the Barrel Harmonic), you then have the combination for the Best possible l-o-n-g distance Accuracy.

But, you have to get the Harmonic first, and then see how it does at long distance.
---

Now, how to get you to the Best possible Barrel Harmonic is relatively easy. You simply use the never improved upon Creighton Audette Load Development Method.
---

It appears from your writing in relating your information to us that you are simply going to a Load Manual and "Randomly Picking" a Load to try. Not actually Developing a Load with your specific Components in your specific Rifle.

If that is true, the odds are that you have "maybe" 10 chances in 360 of hitting a Randomly Picked Load that will be accurate. About 5 chances on each end of a Harmonic. So, you can keep Randomly trying, or Develop the Load properly from the start.

By the way, don't get duped into the "ocw" nonsense put out by rookie green. It has enough changes in the actual Creighton Audette Method to "degrade" the possibility of your finding the best possible accuracy.

Best of luck to you.

Hot Core, my hat is off to you... wonderful job of explaining the situation here!

Assuming your not bumping the lands, and have some magazine space to play with...........
It's time to play with your seating depth. Keeping everything else the same, work in .010 increments longer and SHORTER from where you are now. This is where the various "ogive locating" measuring tools come into play, as it's the ogive to base (ogive to lands) distance that counts, not the tip to base (OAL) measurment (this does matter for magazine usage). You can tune the harmonics this way

This is a strange post! I have been telling guys to put the chrony in a drawer and find the most accurate load first. Best bullet, powder, primer and yes, you are right, best harmonics.
I have been derided and have taken a beating over that. Yet all of you are now saying the right thing. WHAT HAPPENED?
This post has the best answers I have ever read here and I applaud all of you for it.
PUT THE CHRONY AWAY until the best load is found.

First off, did you shoot enough groups to prove a statistically significant difference in accuracy? One group proves absolutely nothing.

How many shots did you fire to calculate SD? YOU CANNOT CALCULATE A MEANINGFUL SD WITH ONLY 3 SHOTS OR 5 SHOTS.

Assuming we are talking about a bolt gun, I'm wondering if there is something wrong with the gun, like a bedding problem or a terrible throat, or maybe gross runout on the loaded rounds. A decent bolt gun should shoot 1.5 MOA with just about any load you pick from a manual.

There's only been a few times that I've encountered shotgun patterns with jacketed bullets. One was a custom TC barrel with a grossly oversize chamber that wasn't even concentric with the barrel. Another was a Ruger 308 ultra-light with its pencil thin barrel and a 0.312" throat. Another was with ball powders in a TC 7-30 -- and those loads had high SD and vertical stringing. Another was the original Barnes X -- which also had high SD.

quote:

Originally posted by Strut10:
I really don't want to obsess on this. I really don't. But things just keep getting curiouser and curiouser.

I agree with you guys, when it comes to extreme spread, that it is not the end-all indicator of which load will shoot and which will not. I'm putting every load on paper and letting that tell the tale instead of the chrono. Period.

Now......here's what I ran into today. I shot a particular batch of loads that were well within acceptable pressure parameters. Here are the numbers for the string:

avg vel: 2933 fps
ext spr: 8.52 fps
std dev: 3.87 fps
group: 4.6"

How in the heck can a load that is so ridiculously uniform group so crappy??????

Bullets out of balance??

Strut10 ----- It is obvious that your barrel does not like the bullet you are shooting, regardless of how consistent your load tests. It may be bullet size, barrel or maybe even you. Try another bullet, either make or size and see what you get. Good luck and good shooting.

To address a few of your concerns.........

The loads I am shooting that give miserable accuracy are all from a single can of IMR-4320.

I arrived at a starting load from a book. Past that I have increased the charge weight by 0.5 gr. at a time (over what is now a 5.0 gr span).

The bullet is a Sierra 250 gr. Game King BT.

The gun is an A-Bolt Stainless Stalker in .375 Wby

With both IMR-4350 and H-414 I have so far gotten 5-shot groups at 100 yds of 1.6" and 1.4", respectively. So, although not yet stellar.....the gun will shoot.

I am not using the chrono for a particular purpose other than to log the physical & statistical values of each load. If a load will shoot I don't care how fast it is.

The box mag on the A-Bolt doesn't allow me much room to play with C.O.L. They're too darned short already and I've got them just clearing the box.

Hot Core........ Daggone!! What a well done explanation. I even think I understand a lot of what you said.

Like I said......I really don't wanna obsess over this and I won't. Just struck me as funny that I could load over such a wide range of charge weights with the 4320 and not get one group to go under 3" at 100 yds. while about anything else I try will not group much larger 1.75". Curious observation....that's all.

A small extreme spread is more an indicator of the quality or the ammo assembly techniques. Accureacy and precision are the interface of the shooter and the weapon.

quote:

Originally posted by bfrshooter:
...I have been telling guys to put the chrony in a drawer and find the most accurate load first. Best bullet, powder, primer and yes, you are right, best harmonics. I have been derided and have taken a beating over that. Yet all of you are now saying the right thing. WHAT HAPPENED?...

Hey bfrshooter, Perhaps I've missed your posts on those comments, because I don't look at all of them. Is it possible you were posting that on a "different Board" and just thought it was here?

It used to be a whole lot of folks thought(and tried to convince others) that you could not make good Reloads if you did not own a chronograph. Of course that was simply a misunderstanding of what a chronograph was actually good for.

quote:

Originally posted by Strut10:
...I arrived at a starting load from a book. Past that I have increased the charge weight by 0.5 gr. at a time (over what is now a 5.0 gr span).

The bullet is a Sierra 250 gr. Game King BT...

Hey Strut10, Good for you. Glad to see you are actually Developing the Load. And I'm glad you could understand what I was trying to get across.

That being the situation, "phurley5" might be close to the answer. Your rifle might just not like that Sierra Bullet.

It might just not like that specific weight and prefer something just a bit different. Try one box of Hornady or Speer bullets and see how they do, or get some different weight Sierras.

By the way, I've found some lots of Nosler Partitions to be more accurate than Ballistic Tips in some of my rifles. Strange situation, but that is the way it goes sometimes.
---

For what it is worth, the larger calibers are "normally" fairly easy to get good Loads developed for. So, it could also be something like "popenmann" mentioned. If that is the situation, you will have your hands full getting it sorted out.

Best of luck to you.
---

Thank you 308Sako. I saved the link to this thread, so I won't have to enter it all again the next time it comes up.

quote:

This is a strange post! I have been telling guys to put the chrony in a drawer and find the most accurate load first. Best bullet, powder, primer and yes, you are right, best harmonics.
I have been derided and have taken a beating over that. Yet all of you are now saying the right thing. WHAT HAPPENED?

welcome to AR!

I have a sim. issue w/ 225gr bullets in my .338-06. This rifle will go an honest 1moa w/ 210grNps & 250gr anythings, but I have to slow a 225gr bullet down to 2500fps to get it into 1.5moa range. I've tried 4 diff. powders & 3 diff. 225gr bullets, no luck. So I just stick w/ the 210grNp or 250gr Hornady, SGS or NP & be happy.
Strut, you bbl. doesn't seem to like IMR4320 much so why leep at it? Life's too short, go w/ the loads that are proving accurate & work from there.

quote:

Originally posted by fredj338:

Strut, you bbl. doesn't seem to like IMR4320 much so why keep at it?

Fred......

I kept at it because the 4320 was giving good velocities (here we go again with the chrono......) with seemingly, very moderate pressure. It also generates a noticably kinder recoil imuplse. I just assumed that at some point, things would level out and the stuff would shoot. Wrong. I have moved on.

There is one thing I forgot about---bullet runout! For accuracy you don't want any more then .002" runout. The Weatherby cases are very prone to get a bend in the shoulder. The cause are dies that size the neck too much and an expander that is hard to pull back out. My .300 would get gross runout until I sent the dies back with fired cases. Redding lapped the dies for minimum neck sizing so the expander hardly touched. That one thing alone took me down to consistant 1/2" groups.
I would get a set of dies with the collar sizer and get a selection of collars so no expander is needed.

When I go to work up a load usually loads for a rifle I leave the Chrono at home. Only after I get a load with the accuracy I want do I run it over the Chrono. Simply to determine the velocity. If the velocity is in the range I want fine. If not I keep looking. I don't care about the spread. So what if the spread is small if the bullets leave the barrel at the wrong spot in the vibration.
I will also then shoot a 300-400yd group to verify.

quote:

Originally posted by ramrod340:
So what if the spread is small if the bullets leave the barrel at the wrong spot in the vibration.

Precisely, so I have found out.

I'd take some pics to show you "so what", but I ain't in the practice of flashing 4 and 5 inch groups around.

OH no, if you really want to start giving yourself mental problems, start measuring for runout.
Find a load that shoots well first, then look to vel./sd/es. I missed somewhere what round this was for but I go w/ powders that pretty much fill the case or slightly comprssed. Lightly prep the brass (no neck turning, etc) load up bullets of known accuracy then shoot for 3 shot groups @ 100. I chrono all along the way but mostly to track spikes or anomalies in vel. Anything giving more than 2moa after initial testing is pretty much scrapped right away. If vel. isn't where I want, I'll look to go to a diff. powder but only if I am more than 100fps from where I think it should be.

Hot Core,
Great post, in easy to understand language.

I absolutely love the idea of the Creighton Audette method. I think it is the best way to develop loads....

But my only problem is the that fact our rifle range is only set up for 100 yards. I tried the method at a 100yards for a 270, but I didn't get the expected information from the test after two different ladders.

So I have taken a whole new approach to my load technique. I take all of my reloading gear to the range and work up loads right there.

I normally pick the bullet and powder that I want to use for a starting point. You have to start somewhere, even with the ladder method.

I then shoot a three shot group. There is plenty of info to get from that group.
In a nutshell what I have found is:

-Velocity, is this load where I want it to be? Change powder charge or powders if it isn't.
You can tell this after the first shot.

-Vertical or horizontal stringing leads to changing the powder charge or even powder.

-Two tight and one flyer is almost always an indication for a primer change.

-Triangle shape groups that are just a too big leads to changing primer or seating depth. I have been amazed at how switching primers and adjusting seating depth can really tighten up those groups.

-Sometimes a particualr bullet just won't shoot from that particular rifle. Change bullets.

I use a chronograph religiously, but I mainly use it to make sure that I am getting the velocity that I expect from a particular cartridge. I have also found that once I get a load worked up, the ES and SD results are pretty good also. I feel the ES and SD are a result of the good load for that particualr rifle. Not a good ES and SD meaning that the load will shoot in a particular rifle.

Then when it is all said and done, I try to shoot a total three three shot groups and make sure the first one wasn't a fluke.

And after all that, it may be the gun, optics, or shooter causing the problems.

Bullet runout is way more important then some of you seem to think. If the bullet is pointing crooked out of the case, do you think it is going to straighten out when fired? I have news for you---NO! Ask any bench rest shooter.
The weatherby is the hardest case to keep straight due to the radiused shoulder.
Drive yourself nuts and cure the problem or don't ask!

quote:

Originally posted by SDhunter:
Hot Core,
Great post, in easy to understand language.

I absolutely love the idea of the Creighton Audette method. I think it is the best way to develop loads....

But my only problem is the that fact our rifle range is only set up for 100 yards. I tried the method at a 100yards for a 270, but I didn't get the expected information from the test after two different ladders.

So I have taken a whole new approach to my load technique. I take all of my reloading gear to the range and work up loads right there.

I normally pick the bullet and powder that I want to use for a starting point. You have to start somewhere, even with the ladder method.

I then shoot a three shot group. There is plenty of info to get from that group.
In a nutshell what I have found is:

-Velocity, is this load where I want it to be? Change powder charge or powders if it isn't.
You can tell this after the first shot.

-Vertical or horizontal stringing leads to changing the powder charge or even powder.

-Two tight and one flyer is almost always an indication for a primer change.

-Triangle shape groups that are just a too big leads to changing primer or seating depth. I have been amazed at how switching primers and adjusting seating depth can really tighten up those groups.

-Sometimes a particualr bullet just won't shoot from that particular rifle. Change bullets.

I use a chronograph religiously, but I mainly use it to make sure that I am getting the velocity that I expect from a particular cartridge. I have also found that once I get a load worked up, the ES and SD results are pretty good also. I feel the ES and SD are a result of the good load for that particualr rifle. Not a good ES and SD meaning that the load will shoot in a particular rifle.

Then when it is all said and done, I try to shoot a total three three shot groups and make sure the first one wasn't a fluke.

And after all that, it may be the gun, optics, or shooter causing the problems.

is the primer really causing this, this is the first i have read this and i have this problem in my 300 win mag as well?

0: set bullet .027-.030 off the lands.. seriously... try that.

1: put a folded business card under the barrel, 1-2 from the muzzle... as a pressure point, retest same load

2: CRIMP

jeffe

quote:

Originally posted by 308Sako:
This is why Browning came out with the boss concept, ...Harmonics baby, Harmonics.
.

FN Herstal invented the "Boss" for the sniper rifle and the rifle was retuned, bt an armourer, EVERY time the sniper came backc for his next 500 round block.

Put the chrony away until you find a load that is grouping to your satisfaction. Load up five groups of cartridges with a three grain difference and go shoot. Then choose the best three or five shot group and go from there. Grain up, grain down, bullet seat out , bullet seat in, primer change etc. Get a fairly good starting point and mess with that. Then if you really want to be disappointed drag the chrony out. Your big groups could be shooter error but I'm not going to say that, it's just that no one else has said that.

quote:

Originally posted by Pegleg:
Your big groups could be shooter error but I'm not going to say that, it's just that no one else has said that.

Could be. But it's funny I only screw up when burning IMR-4320.

Well I do it a bit different. I chrony my loads first then shoot for accuracy from the best performers. I have yet to have a load that doesn't shoot accurately in my rifles so it mostly comes down to the least amount of powder for the velocity I want. I have never worried about standard deviation though. Although I havent seen more than about 50fps dif. either.

I'm really one that thinks the chronograph is needed for dangerous game loads when you need to know what your power level is. I believe that when you get the load that shoots good in your gun, then use that. Shoot it to get familiar with what it will do at the various ranges you intend to shoot at and let the the gun and bullet do the work. For hunting at reasonable ranges I really don't think chronographed loads are necessary. Long range shooting and sniper work is a different story. I also hate those damn bore scopes!

Hot Core!!!!!! Some time your war with words is astounding. Have you ever thought of being a presidentual adviser? roger

quote:

Originally posted by bartsche:
Hot Core!!!!!! Some time your war with words is astounding. Have you ever thought of being a presidentual adviser? roger

I have been ripping the local politicians a new one in our hometown newspaper. Got some interesting responses in the last "Weekly Disappointment"(as I refer to the newspaper(? ))

I'd agree there are a few times that a bit more Presidential Advising does seem to be in order. Here they have "saddam hussein" on trial for keeping the terrorists afraid. Easy to Monday-morning-Quarterback the issue and see where running a Squadron of C-130s over an area with Cookie-Cutters(25Kton bombs) might have better results than what is going on right now.

But, I've never seen the Military as "Peace Corps" as some do. Let them be feared Warriors who break things and kill whatever is in the area. Then the terrorists might be as calm as old saddam had them.

Darn near got wound up! So if President Bush is reading this - turn them loose!