Dan Newberry !!!

The more I think about it I get more and more confused.

The way I think you mean is , after reading your homesight is , that the OCW method are primaly for tuning the charge for uniformaty and then tune the barrel whip with depth tuning of the bullet , right ?

And the Audette method is to tune the barrel whip with the powder charge increcments ?

Now for exampels.
lets say that you shoot your OCW 3x... charges at 200-300 yards in the Audette manner , but on three separate targets with a center aming dot , and then plot the shots on a fourth identical target.

If you look at the three Audette targets separatly,
you in theory got somewhere a group of 3-4 shots clusterd ,and that cluster represent the LOAD.

What I think you come up with, in the plotted target, is that you have a 300 yard OCW target but with only one aming dot and 9-12shots
clusterd in the same spot that the Audette method did,
and that is the OCW charge , if I don�t got it wrong.

The way I see it in terms of optimum charge and optimum barrel hamonics , it�s vise versa ,
the Audette longer range must roule out the charges that is not stabel
and you can still see the barrel whip nod.

On the shorter OCW range you could only see barrel harmonics nods,
and on the short range velocity differenses shoulden�t do much in higt.

What your opinion ? , if you ignore the aspect of that the OCW is more informative and have more statistic value than the one row Audette method.

Anders �sterberg SWEDEN

Anders,

Good questions, and I understand what you're saying.

Let's look at it this way:

We'll need to accept a well proven, universal load recipe to begin with. Let's use 57.5 grains of 4350 in the 30-06 with a 165 grain bullet. This load works beautifully in the overwhelming majority of 30-06's, and it meets the criteria for an OCW load.

Now, let's say you're a shooter who wants to develop a load using 4350 and the 165 grain bullet in your 30-06. You're at the shooting range, hoping to find a good load for your rifle.

You decide to try both the OCW method and the Audette method.

You fire five graduations for the OCW method, using 56.5, 56.8, 57.1, 57.4, and 57.7 grains in round robin fashion. You note that the three groups on the end seem to all hit the target in the same place. You decide, according to the OCW instructions that 57.4 grains is the OCW. (That's close enough, of course).

Then, you decide to try the 20 shot Audette method. You begin with 54.0 grains, and load one shot each in .3 grain increments all the way up to 59.5 grains. You commence firing from 300 yards away. Let's assume there is no wind whatsoever, and that your barrel doesn't heat up too much or foul excessively (some pretty generous givens, wouldn't you say? ) ...

You fire your shots without pulling any flyers (likely another pie in the sky!) and the lighting and wind conditions remain favorable throughout the 20 shot string. (pie in the sky a la mode!)

As you approach the true OCW of 57.5 grains the liklihood of the 57.3, 57.6, and 57.9 shots being released on a fast portion of the vibration whip of the barrel is relatively high. In this case, these three shots would string. At 100 yards, this string might be 3/4" long. At 300 yards this string would be over two inches long!

You then ignore the 57.3, 57.6, and 57.9 grains charges and look elsewhere on the target for some shots that grouped closer together. Somewhere in the 20 shot string you will find three or four--or even five shots that come in under two inches. But how did they do this? They grouped well because of a favorable barrel vibration, which threw these shots together even though their consistency wasn't as tight as the 57.3 through 57.9 grain charges.

With the OCW method at 100 yards, even if the bullets exit the muzzle in an unfriendly portion of the barrel's vibration whip, you'll still be able to tell (with the three shots) where the group has formed. Usually, when you find the center of the OCW zone, the three shot group will tighten. It may not, however, due to pulled shots, a fouled or heating barrel, etc. But the center group of the three groups which strike the target in the same spot will be the optimal charge weight--no matter the group sizes.

Someone might ask "What about shooting the 20 shot Audette method at 100 yards?"
This would reduce the wind factor, of course. But the tendency for favorable barrel vibrations to put inconsistent shots together still exists. The tendency for unfavorable barrel vibrations to throw consistent shots well away from each other is still there. In short, the propensity to come to the wrong conclusion for you load is present at 100 yards, just like at 300 with the Audette method.

By first identifying the best powder charge (the charge that ignites and burns more consistently than any greater or lesser charge in that application), and then depth tuning the load to take advantage of a favorable vibration node, you're getting a load at least twice as good as an Audette load. You will not have skipped over the optimal powder charge just to take advantage of a favorable vibration node--you'll have the best powder charge, and a node tuned load.

Dan Newberry
green 788

Dan
Your words making sense, as they always do
and I feel a lot calmer.

If I should shoot a ladder serie of loads like in the manner of LTR DAVID on snipershide

http://216.219.200.59/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=13&t=000425

and then depht tune for accuracy from there,, should you be comfortabele with that method?

A.�

Anders,

If everything goes well during the 20 shot Audette string, and you don't fire it from too far away (I prefer 100 yards), then it may yield useful results. Many folks over the years have found good loads using the Audette method--but many others have found the method lacking. I've heard of folks shooting two seperate Audette tests and coming to a different conclusion for each target--not good...

Something else to consider... In order to get 20 graduations in 1% increments for the Audette test, you have to start pretty low. In my opinion, the first 7 to 12 shots are likely to be wasted. Even if you found a friendly node early in the string, you'll have identified an underpowered charge for the cartridge.

I like to check two or three loading manuals, and get a good idea of the maximum powder charge. Then back down 7 to 10 percent and load one cartridge, add 2% and load another cartridge, and add 2% to that one for the third charge. These three rounds can be used for sighters/foulers, and will show you if there are any pressure signs.

Then add 2% to that third round's charge weight, and load three cartridges. Now, start moving up in smaller increments of .7 to 1 percent, loading three of each charge weight. This will give you three chances to put each tested charge weight where it should be, instead of only one chance as with the Audette test.

Again, if there is a friendly node down low in the powder weights, I'm not interested in it. We would normally want our rifles to perform as well as the cartridge is capable of. Generally, you'll not find a true, repeatable node in the low charge weights. As Savage 99 mentioned in another thread, the best performing loads are practically always at the upper end of the pressure curve. (That's how the cartridges and powders were designed to work).

So if you want to do the 20 shot Audette test, it might net good results, but then again it might not. I prefer three shots of each charge graduation for a more definitive conclusion.

Best of luck, and let us know how things go...

Dan

Dan
what I ment was that I was thinking of shooting a string of shots with lets say 0,5 grains increasments over a chronograf and determin the OCW by finding a platu in the velocity curve and then make the accuracy tune by seat the bullet deaper to find the barrel harmonic nod.

A.�

That might do it for you... I must admit to never using a chronograph for initial load development.

An engineer that I've been corrosponding with has been doing some of his own testing, and he has actually found that the OCW zone does not correlate with the chronograph data. In other words, he found in initial testing that the most stable velocties did not necessarily share the same point of impact on the target.

I realize that that is a puzzler, for sure. He gave me the "engineer's explanation" as to why he surmised this would be, but I couldn't understand it well enough to go on record here with the theory. (Yet, but I'm working on it!)

You might find that very tight velocities will land you in the OCW zone, in your own case. I don't know.

Why not chronograph all of the loads, and shoot them in round robin groups of three (as mentioned in the OCW instructions) and let us know if consistent velocities mean consistent points of impact for you. I would be very interested to know this, as I've not approached this with chronograph data as of yet.

Take care, and keep us informed...

Dan

This is a very interesting thread so far. I'm looking forward to the additional input.

I tested it today !!

A wile ago I did a OCW test with a Norma 130g bullet and vihtavuori N-140 powder ( 308 win ), and it did exactly proceded the way that Dan said it would,
I got actually four groups that hit the same spot and it was , charge 48,8 - 49,1 - 49,4 -49,7 but on 50grains the group open to the double and vent to the right and on 50,3 eaven more to the right so a tok the 49,1 as mean charge , but I didn�t mesure the Vo so I reshot the low , mean, and high charge in the same manner today.

I loaded three of each load and shot it in the round robin facion and wrote down the velocaty on each shot.

48,8 grains= Vo 2965-2912-2906 average=2927 ES=59
49,1 grains= Vo 2955-2938-2912 average=2935 ES=43
49,4 grains= Vo 2981-2955-2966 average=2967 ES=26

All groups hit whitin 0,7 inch of each other in referens to the aiming spot, but was sringed in the horisontal plane ,

the 48,8 group mesured 2,0 inch in horisontal plane but only 0,6 in the vertical plane

the 49,1 group was 1,6 in horisontal and 0,8 in vertical .

the 49,4 was 0,6 Horisontal and 0,6 in Vertical

It seams that the horisontal sringing got better with the lower ES.

I think I should go up a bit and try if the ES shrink eaven further , but that will be an other time.

A.�

Thanks for sharing your information, Anders.

What distance did you shoot these groups at?

It looks to me like 49.3 would be closer to the OCW, and your chronograph numbers would be looking better there too.

If you shot these groups at 200 to 300 yards, that might explain some of the horizontal dispersion. Even when the wind seems calm, unless you have wind flags it is hard to be sure what is really going on.

I think if you will depth tune using the 49.3 grain charge, you will be able to tighten the groups even more.

Take care, and keep us posted...

Dan

Dan
The range was 100 meters.

the groups was much better in the first try , but after that I have done a rebedding of the stock with pillars an I think it shanged the harmonics to the negative side , at least for this load.

I think I should go up a bit in load weight, maybe 49,7 - 50,0 - 50,3 again , and se if the ES would go down ?
what do you think is a reasonaly good ES ?

One thing I�v learned is that one could not shoot just one shot a load in the Audette manner and think you know anything of value , ES and group vise .
A.�

Anders,

As I'm sure you know, you're right on top of maximum load pressure with 50 grains. But I think if you want to redevelop the load--now that the rifle has been pillar bedded--that would be a good idea.

I wouldn't worry about extreme spreads. Read my post regarding chronograph data in the "watermelon seed, smoke ring" thread here, and that will explain why. In short, the extreme spreads can be manipulated after identifying the OCW by way of depth tuning. Use target data only for identifying the OCW, and then depth tune the load for tightest group. Then look at the extreme spread, and see how it looks (if you're curious!) . If the load is performing well, the numbers are only that--numbers. If the load is not performing, all the good numbers in the world mean nothing.

Shoot the OCW round robin test with three shots each of 49.2, 49.6, 50.0, 50.4, and 50.8 grains of the N140. Shoot the 50+ grain charges only if the preceeding charge showed no pressure signs. Seat the bullet a caliber's depth into the case for initial testing. Don't try to seat the 130 grain bullet long, I'm fairly certain that it will do its best about a caliber's depth (.30 inches) into the case.

Best of luck in your testing, and please post your results.

Take care,

Dan

Hmm?!
I�v not decided yet if I should redo the whole OCW test or only go for seating depth , it leaning for the depth tune , and it would be intresting to se how the Vo and ES should react on the seating depth change.

I�l keep you posted.

A.�