The basic notion is that for every load recipe (cartridge, bullet, powder) there is an optimal amount of that powder which will ignite and burn most consistently. I call this the Optimal Charge Weight, or OCW. An example is the 270 win. using 130 grain bullets and IMR 4350. The OCW is 55 grains of the 4350. I discovered this via the method I'll outline below, but I note that Winchester seems to have discovered it long before me. They used to use this exact charge of IMR 4350 in their factory 130 grain loads.

What I'm saying is a bit controversial. Most folks are of the school of thought that all rifles are different, and the perfect charge of powder for one will not be the same as for the next. That's true to a degree, but I believe that the fine tuning may be better achieved with primer and seating depth variations, keeping the OCW fairly unchanged.

I will continue this thread with another post which outlines a sort of "modified Audette method" for finding the OCW for a given recipe.

My reason for continuing the thread with another post is that I don't want to lose this introduction if my post turns out to be a bit long.

Please stay with me here, and please do offer any criticisms and dissenting opinions, and reasons for such. I'm interested in opposing viewpoints, as well as the words of any of you who have perhaps been using a similar method of load development.

Creighton Audette used a method for finding the "sweet spot" of a particular load by shooting at a fixed point at 300 yards. His loads consisted of graduated charge weights, with cases, bullets, and primers being the same. He would shoot, in the 270 win example: 53.2, 53.5, 53.8, 54.1, 54.4, 54.7, 55.0, 55.3, etc...

What Audette looked for through the spotting scope was a "cluster" of bullet strikes in the vertical string on the target. In the above example, ideally, there would be a tighter cluster from 54.7 to 55.3 than in anything previous or after.

One problem with this method is that one must really be sure of his prowess on the trigger. A couple of pulled shots would spoil the whole test. Another problem is that the various charge weights would not necessarily string vertically at 300 yards. I think we have all seen load variations cause as much lateral movement as vertical.

I'm open to suggestions for improvement of this system, but here is my own method as I currently use it. It has worked for me so far, but that doesn't mean there isn't room for improvement:

I like to use graph paper with the 1/4" squares for targets for this purpose. The best aiming point is a black square, drawn by a marker. The best size for this square will depend on your riflescope's power. Set your scope to maximum power, and experiment with square sizes until you have one which you can *just* quarter at 100 yards (or 200 yards if you prefer to test at that range). You want the square to be big enough for you to see all four white quarters around your crosshairs, but small enough that there isn't a lot of wobble room inside the box.

You begin your load testing with all equal components: brass, bullets, primers, and seating depth. Make up three of each charge weight. In an example let's say we're testing Varget in the .243 win with the 85 grain Sierra bullet. I'm currently making the ammo for this very test, and some of you here helped with the parameters I chose. When I get to the range, I'll have three each of the following: 37.0, 37.3, 37.6, 37.9, 38.2, 38.5, and 38.8. I will of course clean the rifle between each three shot group, and foul it with one shot before firing the next three shot group.

I'll have in this example seven groups. Most of us would look for the best of the seven, and call it done. In some cases, we'd be right, but in others, perhaps not.

After all groups are complete, with called flyers noted (this should still leave two shots in good standing), we would now compare the *point of impact* of each group. What we are looking for at this point is not the tightest group of the seven. We are looking for the *three* groups which land closest to the same place on the individual targets. (Here is where the graph paper comes in handy). In some cases, the best group of the seven will be among this trio of groups, in other cases it won't.

If I happened to notice that I fired a 1/2" three shot group with the 37.0 grain charge, but the three groups which came closest to hitting the target in the same place were the 38.2, 38.5, and 38.8, I would still opt for the mean charge as my OCW: 38.5 grains.

In doing so, I may not have a 1/2 MOA load (YET! we'll get to the fine tuning later..) But what I will have is a load that is *resilient*. Such a load will be much more tolerant of temperature changes (even when using powders which aren't particularly noted for their temperature stability). A resilient load will also be less affected by minor lot to lot variations in brass, powders, etc.

I would much prefer a 3/4 MOA load which isn't finicky to a 1/2 MOA load that was.

Okay, I'm about done here. Thanks for enduring my verbosity.

Another advantage to the OCW method is that your charge weights can vary slightly above and below the mean charge, and you'll still have basic accuracy.

And when your shooting buddies decry the lot to lot variations of components, you'll have no worries.

When I identified the OCW for my 270 using 130 grain bullets and IMR 4350, I tested using WLR primers. I did in fact shoot the best group of all tried with the 53.8 grain charge. But 53.5 and 54.1 were not so good. The 54.1 grain group began a major deviation away from the POI of the 53.5 grain charge.

So I went with the 55 grain charge, and began testing other primers. To shorten the saga, I found that Federal 210's did the trick. The old Model 70 now shoots 1/2 MOA so consistently it's a sin.

As a final fine tuning point, you can adjust the bullet seating depth, or distance from the lands to really bring things into check. Most folks do all of this in reverse order, but I think there is merit in doing them this way. There is nothing whatsoever sacred about distance to lands. Folks often begin with a set length, and proceed with load development until they find a good load, and assume that their rifle just "loves" that distance from the lands...

Of course if you keep everything *just so*, and get downright anal about case prep, lot selection, etc, you can shoot tight groups with just about any charge weight in the normal range.

So there it is. If you're tired of lot variations and weather conditions playing havoc with your pet load, maybe it's time to redevelop, this time, with an eye toward the OCW.

A final point. When using this method with the small cartridges such as the .223 Remington, .2 grain variations would probably be in order.

Dan Newberry
(green 788)

[This message has been edited by green 788 (edited 05-23-2002).]

Sounds like a perfect question for Saeed. He has the equipment and the experience to tell it exactly like it is. Not too many of us have access to the superb testing facility that he uses every day.

Yes, I am interested in his opinions in particular.

green 788

That makes much more sense to me than some of the other methods I've been told to use. I'm new at this so haven't tried too many methods. It allows one variable to be tested at a time, which is cause for good results. Thanks for the info, I've already got it printed.

Hey green 788, My 40+ years of reloading experience disagree with your "OCW" idea.

A recent example might be helpful and I can quote it from memory. I've had a number of 7mmRemMags over the years, so I've spent a lot of Trigger Time with them. My current one hits a SAFE MAX at 4.0gr "less" H1000 than the one I had right before it with a 150gr bullet. And, they both (as well as others) seemed to shoot their best at "their own individual" SAFE MAX level.

I do agree that trying different Primers and Seating Depths is a great "Fine Tuning" technique to hit the Harmonic Apogee (or Perigee as the situation may be).

I'd encourage you to try your "OCW" idea in a few rifles of the same caliber "in your own hands" and you should be able to quickly see that it just doesn't work that way.

There is a similar concept among inexperienced reloaders who think they can log onto a Board and ask, "What is the Best Load for a xxx cartridge?" I know people mean well when they respond to them with a "specific Load", but they are actually hurting that reloader's chances of getting a "Great Load". That rookie would be much better off to just develop his own Load, for his particular rifle, using the various Component Manufacturers Manuals as Guidelines for where to start.

You can select any portion of the barrel/bore dimensions and from a technical standpoint, there is just no way the harmonics from rifle-to-rifle will be the same. They might be close, but just not the exact same.

I'm going to be out of town, so won't be able to respond further for awhile.

Good luck to you in your writing.

------------------
Good hunting and clean 1-shot kills, Hot Core

I must say that if you experienced a 4 grain variance with two rifles of the same chambering, one was well above, or well below the norm.

I can't actually claim credit for the method, merely the acronym. As mentioned earlier, Audette made famous the basis for this notion.

When a major ammo maker puts together a load, they do so with an eye toward achieving a charge weight that ignites and burns as consistently as possible. For all normal rifles, the load will perform adequately. In some, the load will perform extremely well.

In your rifle which seemed to like the abnormal charge, it may be necessary to go to a faster (or slower) powder in order to identify a good OCW. What you'll be looking for is a charge weight that will tolerate a + or - .3 grain variance from the mean, and still group respectably. Such a powder and charge are almost certain to exist.

You will then have a load which can accomodate temperature changes that would simulate a powder charge variance of + or - .3 grains.

I have tested the method in three rifles. One 270 win, and two .243's. My .243 loads can shoot, believe it or not, into 3/4 MOA using Winchester, Hornady, and Norma brass in the same group.

Again, you reach a plateau along the continuum of charge increases where things begin to level off. The length of this plateau would of course depend on the load and the powder being used. It does, however, exist.

Some rifles may not be able to take advantage of a standardized OCW but they will be the exceptions rather than the rule.

It may help my point to mention an excellent factory load here. Again, a 270 load, it's the Winchester 130 grain Super-X power point. The cheapest of Winchester's offerings, there is 59.2 to 59.6 grains of *some* kind of ball powder in that load. My 270 shoots this factory load, believe it or not, into very consistent 3/4 MOA and *under* groups. But wait. A friend's Ruger 77 shoots this load under MOA as well. And a recent article in Gun World mentioned this particular load as being the most accurate of all loads tested in a particular rifle, shooting under MOA. And a shooter who posts at this forum has mentioned exceptional accuracy with this load in his 270.

That Super X load is an optimized load. Its powder charge (I wish I knew what powder they were using!) obviously burns with extreme consistency. Regardless of individual barrel whip, a consistent load will release its bullets in the same general area of the whip cycle. Agreed that it is best for the bullet to release when the barrel is at a more stationary part of the cycle, but I believe (although I didn't use to) that OAL changes are all that are needed to effect the point of release on the barrel's whip cycle.

Dan Newberry
green 788

Dan,

I find your effort in defining an optimal operational threshold intriguing. It amounts to defining metrics and correlation from an engineering perspective. In order to abide by your request I shall withhold my take on your project.

In order to generate the highest degree of success in the identification of any metrics is to properly establish a viable hypothesis and prove or disprove that premise. It appears that you have created just that in your approach. Second, it requires the use of identifying each of the dynamic and static variables affecting your hypothesis. I have not been able to successfully identify those attributes in your premise however.

Nevertheless, I trust you will share your outcomes and findings with us and good luck in your project.

------------------
Best regards,
Alex

Democracy is two wolves and a lamb voting on what to have for lunch.
Liberty is a well-armed lamb contesting the vote! - Benjamin Franklin 1759

Dan, Check out Jim Ristow's comments here:

http://www.shootingsoftware.com/ftp/chrontech.txt

Some interesting thoughts there on load development and node width for stability.

When I discussed the Audette with Jim he immediately brought up the "operator error" problem. It does seem most people can't shoot well enough to support the method. Of course I could do it, I'm sure!

REL

The physics of Audette's method make perfect sense, if you can control the other variables.

There are easier ways.

Audette's method is an OFAT experiment: One Factor At a Time. There are methods for simultaneously accounting for the effects of more then one variable, and they are considerably more efficient.

One very cool one is Response Surface Modeling. It lets you fiddle with two variables at once. One of the keys to using it is to look for what you just described: a broad, stable region.

I think you're on the right track. Keep at it.

GREEN 788
Please excuse any ingnorance here but I am 'assuming' that this method searches for optimal accuracy without regard for velocity. Is this true. One thing I have seen on some post and had some personal expierence with is that the same componets, but different charges of same powder produce a peak and valley type of chart. At the top of the peak indicating accuracy and naturally increasing the load increases velocity. This peak and valley effect occurs throughout a test. Ideally I would want the most accuracy with the most reasonable velocity. I might be in the dark here..can you explain more. Thanks

788 forgot to add that I think this theory is very interesting and appealing..I just want to know more and appreciate you posting it.

Regarding velocity, you're right. You begin with a set of parameters--a starting charge taken from a reputable loading data manual, and of course a max charge. You'll have a rough idea of the velocity ball park you're going to be in based on the numbers published in the load manual.

If you're looking for a particularly fast load, you will want to select a powder that pushes the bullet faster. If you're less concerned about speed, you can choose a powder that attains lower velocities.

Further, if there is no discernible OCW with a particular powder you test, you will certainly want to test a different powder.

As for the individual shooter's talent, and its effect on such a test. I hesitate to say this at the risk of sounding at best pompous, and at worst cruel, but... If you aren't able to "hold hard" as they say--at least well enough the execute the test, then you will probably not be able to enjoy the benefits of an optimized load anyway. I think it is important that your load testing be done by you personally--not a machine rest or other shooter.

The Nosler data book is my personal favorite. They tell you which was the most accurate powder tested, and then go on to mention the most accurate load tested. In every case I'm aware of, the "most accurate powder/most accurate load" recipe from the Nosler manual makes for a good load--regardless (heresy!!) of the rifle it has been shot in.

For those of you who haven't tried these recipies, I would urge you to do so. Most if not all of these loads seem tolerant of the small charge variances. These may be OCW loads staring us in the face.

Also, if you have a 270, try the Winchester Power Point "Super-X" 130 grain ammo. It's cheap (about 11 bucks a box at Walmart) and it shoots incredibly well in a number of different rifles I'm aware of. This load of course doesn't take advantage of fire-formed, match prepped, individually weighed cases. It shoots extremely well. How can it break all the "rules" and still shoot so well? Please try it if you're equipped to do so. The sterling performance of a factory load such as this one seems to indicate that there can be extremely versatile and resilient load recipes.

Thanks for the interest,

Dan

Dan,

As someone about to start developing a new load with new components in a .308Win, I find your ideas very interesting. At this stage I am simply not expirienced enough to comment on its general validity.
However I would take issue with your statement in your last post where you say it is important for the shooter to do his own load developement and not use a machine rest etc. Surely if your concept is correct, the burning characteristics of the powder and its effect on the groups will be consistant regardless of who or how the group is fired?
Sure a bad marksman will probably mask the effect, but it will still occur; the use of a machine rest will simply remove the human variable all together and resulting consistancy must be desirable in tests such as these?

Peter

Green 788,

I somewhat agree with your thinking, but I believe what you may be observing is what I call OSR, or Optimal Spin Rate of the bullet. That is, for every bullet, there is an optimal spin rate of stabilization. The spin rate being governed by velocity and rifling twist.

Some years ago I built a 7x57 sporter using one of those surplus 19 1/2 inch DWM barrels from Numrich Arms. It came with a 1 turn in 8.6 inch twist. I wanted to shoot 139 grain Hornady SP's. All of the literature said you couldn't shoot these bullets out of that barrel with any accuracy. After loading up some 2,850 fps loads and testing them I was inclined to agree - 4 to 6 inch groups. Not to be discouraged, I began searching for a way to remedy the situation without going to a heavier bullet. The answer came by observing the "accuracy loads" for the 139 grain Hornady in various 7mm cartridges listed in my old 45th edition Lyman Reloading Manual. Working with the muzzle velocity and rifling twist given for each test gun, I arrived at an OSR of around 180,000 rpm for this bullet in the accuracy loads listed. Using my data, I computed my spin rate was 220,000 rpm. I figured if I could get my spin rate down to near 180k I would solve my problem.

I made some rough calculations based on fps per grain of powder and reduced my loads accordingly. Range results were gratifying, as the first 3 shot string fell in to .75 inches. Velocity was 2,600 fps. I haven't changed it since!

Bobster,

That's an interesting concept, and it does make sense from the standpoint of physics. I won't argue that it may well a particular spin rate that the OCW achieves.

I have noted, however, that the particular .308 match load cited below seems to shoot as well in a 1:12 twist as it does in a 1:10 twist.

175 grain Sierra Matchking
45.0 grains of Varget
CCI BR primer
Winchester case

This load is the one to beat for supreme accuracy with the 175 grain Matchking.

One shooter at Snipershide who I convinced to try this recipe shot groups in the .2's, this with a 1:12 twist rifle. My Savage 10FP shoots this recipe into .2's as well (.3's at worst), and it has a 1:10 twist.

I'm not sure what the spin rate difference would be here, however.

green 788

I think Bobster definately introduced one problem... However, I also think you'll find that some powders will operate accurately in a broad pressure (velocity range) and others will operate in a much narrower pressure range.

Green,
I'm not sure that this data will support or deny your idea, you decide.
In process of trying to work up a load for my rifle I settled on 39.5 grains of H380 pushing a 55 grn bullet seated for a COL of 2.350 inches. That is .080 from the rifling in my gun. I wanted to play with seating depth to try for more accuracy. Shot just under .7 @ 100yrds.The day I shot the following rounds had variable gusty winds so my accuracy is in question.
.010 from lands 3707, 3698, 3684, 3700, 3680, fps. ave 3692 fps.
.020 from lands 3728, 3682, 3730, 3692,
3675, fps. ave 3701 fps.
.030 from lands 3739, 3709, 3710, 3753,
3743, fps. ave 3730 fps.
What are your thoughts.
Burt

Of course shortening the OAL will increase pressure because you are reducing the interior dimensions of your case. Increasing the bearing surface by seating deeper will cause pressure to increase as well. This explains your velocity increase as you seat the bullet deeper.

I'm assuming you're talking about a 22-250 Ackley. If you're using 39.5 grains of H380 in a standard 22-250, you're way over max with that.

Seating the bullets deeper will give you better accuracy in light, fast varmint type calibers. Stay with the shorter OAL, clean your rifle well with JB bore paste. Leave a controlled amount of copper in the rifling--usually just enough to see the "orange" in the grooves when you look into the muzzle. Don't let copper build up, but don't remove all of it either. Allow a couple of minutes between shots when shooting for group, unless you're shooting in the hot sun--allow about five minutes then. Avoid Remington brass--I've found that neck irregularities make it inferior to Winchester and Frontier (from fired Hornady factory ammo). Federal cases do well for most folks too.

For a possible OCW with Nosler's "most accurate powder tested," try RL ("Reloder") 15. Use 34.5 grains for around 3500 fps. The max charge would be 38.5 according to the Nosler manual (38.5 would yield around 3800 fps). I'm inexperienced with the 22-250 AI. That's a reference from the Nosler manual for you to use as you wish.

Let me know how things go.

green 788

Green,

Yes I am loading a 22-250 not an AI.

Your comment on being overmax is concerning.
I assume what you mean by being overmax has nothing to do with OCW. My Speer #13 shows 42.0 max, Lyman #47 - 40.0, Hodgdon website - 41.0, label on Hodgdon powder - 41.0, Hodgdon #26 - 37.0. This is the info I have available, are there better sources out there? I found no real pressure signs at this loading.

As for your OCW idea, one of the ideas I understood from what you laid out was that minor variations in basic cartridge loadings should not change performance. I understand your comment on changing case capacity and bearing surface, what I was reading into my data: I must not be at OCW or my accuracy and velocity would not have changed so noticably.

For my intended purpose I would like to get about a 1 inch group @ 200 yards and be around 3400-3500 fps.

Burt

Green,

Its unfair to ask for input from someone without giving them as mush info as possible, sorry. I think far faster than I type and my memory is perfect, just real short.

I was also shooting a similar load, 35.0 grns of Varget without the velocity changes, ave 3570 fps.

The groups from both loads did show signs of getting smaller with shorter OAL.

Had good results from IMR 4895 in this cartridge, I guess I will have to buy more. I will pick up some Reloader as well.

This may be off the subject, but, I am using CCI primers, mag primer with H380. I read about all the other primers used in other posts but almost nothing on CCI. Are they not as good?

Burt

Burt,

The CCI primers are among the best in my opinion.

I checked your sources for the H380 charge and you're correct. For whatever the reason, the Nosler #4 manual lists 35.5 grains of H380 with the 55 grain BT as the maximum charge in the 22-250. That does, on second glance, seem very conservative. FWIW, they list the 35.5 grain charge as the most accurate load tested, and the H380 as the most accurate powder. It might be worth a try. Velocity would be in the 3500 fps range.

Did you know that the makers of the game Trivial Pursuit deliberately inserted some wrong answers into the questions so that if someone were to plagiarize thier data, they could be more easily identified? Maybe Nosler did this in this case, I don't know. I do believe your load is safe. Sorry about the confusion.

All that said, I have noted good results with the suggested loads on the Hodgdon cannisters. Although Hodgdon claims that they don't test for accuracy, only pressure, the loads I've copied from their powder can lables have always performed very well.

Take care, let me know how things go...

Dan
(green 788)

green 788,

I must agree, the 175 Matchking is hard to beat. Frankly, I have found that it shoots well over a range of velocities with different powders. Perhaps bullet forms like the long boat-tails have a broader range of velocities they will stabilize in due to their more uniform distribution of mass (balance) and aerodynamics. Forms like short,flat-based spitzers with long ogives and narrow bearing surfaces may be a bit more sensitive to spin rates and only "like" a narrow range.

Bobster