[MikeG]

After seeing many of Nick's posts espousing the "Optimum Charge Weight" method of load development by Dan Newberry, I finally got around to reading about it here:

http://optimalchargeweight.embarqspace.com/

Dan's observations on methods of picking accurate loads were an eye-opener to me. What absolutely convinced me of his methodology was the further work by another experimenter, Chris Long, whose work can be found here:

http://www.the-long-family.com/

While Chris' writing may be a bit much for the casual plinker, it is refreshing to get some actual theory behind why something may or may not work. As opposed to, say, a bunch of half-truths and myths that have been repeated for the better part of a century - the all-too-common "output" of what passes for the majority of gun magazines these days. Naturally, not all writers have an engineering background; and certainly, very few engineers I know can write worth a darn. But, they *ought* to occasionally get together and vet each other's work.... OK, rant off.

I suggest giving both a read, if you can stand this sort of detail. To save Nick a lot of typing in the future, this post is going to be made into a "sticky" to see if it helps people. I would also like to get commentary from others who have started using these methods.

I have my own questions about applying the method, especially with cast bullets and compressed loads, but am going to mull those over in my head for a bit first.

Discussion on....

 

[marsms]

I'm new to handloading, to be sure, but since I was a boy, I was out shooting all the time with my uncle. He used this very method even back then. He just always called it round robin, simple as that.

Of course, he tried the Audette Ladder method as well...we both agreed it was junk, and it was dropped right then. (Shouldn't actually say it was junk...it has it's place, just not with me).

Even when he had a load worked up for his rifle, he was still out there, testing and re-testing every round (using "his" round robin method...because of course nobody can ever think of anything before you do!) he had ever tested before. Just to be sure, he'd say.

So, I use the same method now as well. I like it alot, even though I haven't found a satisfactory load for my .223 yet, I'll get there...of course, as with most anything else...it's worth a try, eh?

 

[unclenick]

The Audette ladder really needs about 300 yards to work well, while the round robin does not. As Newberry's web site explains, the Audette ladder doesn't work for every gun every time.

This reminds me to point out the round robin isn't just for powder charge adjusting. You can use a starting load (use something safe even with the bullet touching the lands) and increment the seating depth away from the lands and fire the round robin to find your gun's favorite seating depth. Once you have that, then start shooting for the best powder charge.

 

[InRut]

I came across Newberry's OCW method a while back when I was new to reloading. I had a devil of a time trying to figure out why I was getting fliers. I wish in the beginning when I originally started reloading I had knew about it. I ended up starting over with that rifle with his method and now have a load that is very good. It answered some observations, I believe, I saw when I was trying to figure a load out. It is the only way I will approach reloading from this point on.

 

[MZ5]

I love the OCW method. For me, it is so dramatically faster and more efficient at finding good loads for rifles, I don't even think of trying anything else. The idea that the loads are truly 'universal' (some exceptions possible) was brought home for me based on an OCW I got to with my .243 Win. On Dan's site, another fellow wanted to try that powder and bullet weight, so he used information I had posted and (testing low for pressure & safety first) tried my charge weights. Though at first it seemed to not be working, he discovered that a seating depth issue needed to be addressed, IIRC, and then had outstanding accuracy almost exactly where my work-up had shown it to me.

That helped prove to me that the concept will develop loads that are 'portable' to other rifles.

 

[Romey]

I have a question about the OCW method. Is it not the same as "traditional" group shooting just a round robin style?
If so how is it any faster, better or done with less rounds. Its very likely I am missing something about it. Ill wait for answers before giving further thoughts.

 

[unclenick]

There may be nothing new under the sun, and I doubt Newberry would have been the first on the planet to come up with the load round robin for accuracy. It just didn't get popularized the way the Audette Ladder did (which takes even fewer shots when it works, though it doesn't always or it doesn't always work simply, as this thread shows.) Newberry is also interested in finding loads that are charge insensitive and that will match up reasonably well to a number of barrel lengths. Those are the elements that get a little further into the puzzle over what makes something accurate?

 

[Romey]

Thanks guy, Im aware its matching harmonics to load in a sense and realize that Auddette ladder has faults, I have seen a modified version work quite well in BR guns though one failing of it is closer then 300 yards your kind of wasting ammo unless you REALLY have a handle on reading the impact. I.E. reading impacts of a sub MOA rifle at 100 yards is going to show fault in ladder. At any rate I am going to take a known sub MOA load out with loads up and down and see if OCW finds that load for me. IF the wind isnt blowing like today

 

[unclenick]

Creighton Audette himself used to run the ladder at 200 yards back in the 80's, but Randolf Constantine, who really popularized it with his article, suggested 300. In other words, if you're already a champion level BR shooter, you may be able to make it go at 200, but it's a lot tougher than at 300.

 

[MikeG]

I'd say the OCW method spurred Chris Long's new theory on barrel harmonics. The other barrel harmonic theories did not explain why some loads seem to almost universally do well.

Perhaps not a concern if your load is accurate, but I think it is interesting.

 

[Romey]

I agree , all interesting. I did not get a change to shoot rifle today but I usually do a couple times a week so Ill play with he whole concept and see if i can wrap my head around how its different.

 

[M1Garand]

I've always like this method and Chris Long's page is some good reading too. I ran across some interesting reads on long range shooting and the ladder method:

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1696162#Post1696162

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1699588#Post1699588

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1705470#Post1705470

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1713419#Post1713419

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1723219#Post1723219

A lot is much more then I want to get into for hunting rifles, but there is some good info/reading in there. I have tried this but I still prefer the OCW for various reasons, many Newberry points out. When I fired it, I didn't have a spotting scope so I had to drive out to mark the target after each shot. The second time I colored the bullets with sharpies and that made it much easier. By the time I fired the first string, then the second, loaded 5 rounds of the final charges fired those, found the charge I wanted then adjusted seating depths, I had fired quite a few rounds and that's considering everything goes well and data is interpreted correctly. In some of the above threads, some post actual targets but cannot interpret the results. They are then recommended to refire at a further distance. Supposedly the ladder saves bullets over something like the OCW, but I really don't think it does.

 

[ranger335v]

How shooting "round robin" can do a thing that shooting however many rounds you may wish into each target in sequence eludes me.

The only "weakness" of shooting a ladder seems to be any inconsistancy by the shooter can easily to make it impossible to observe the closing and reopening of the charge steps.

The only weakness I see in shooting a ladder test at short ranges, ie, 100 yards, is the difficulty of indentifying each hole later, especially so if the rifle and load has high accuracy to begin with. It's hard to identify individual rounds in a big, sloppy hole!

I've never thought ladder tests should be used to identify the "best" load. Rather, it quickly eliminates charge ranges that WON'T shoot well and aren't worth pursuing. It can quickly identify charge ranges that might be used in an OCW test.

 

[unclenick]

Ranger.

The round robin is to spread out the influence of fouling and heat in the barrel as well as light and temperature conditions and other things that can change as your shooting session progresses. Newberry wants each target subjected as closely as possible to the same collection of those influences as the others. That tends to eliminate them as variables.

Check the ladder in the link I made. You'll see that when the rifle is not on a load sweet spot, the groups don't just suffer greater vertical variance, but also greater randomness. Then, if it's not a rigid benchrest barrel, you wind up having to use some more sophisticated math tools to correctly analyze the trend. It's just more trouble.

At 100 yards you don't see much POI elevation difference due to lower or higher muzzle velocity. At 300 that becomes much more apparent and adds the velocity dependent POI difference to the muzzle motion caused separation. For example, the vertical drop difference for a 175 grain SMK at 2600 fps and 2700 fps is only 0.2 inches at 100 yards, but is 2.5 inches at 300 yards. It's way easier to pick out the ladder's vibration stringing if that velocity change in POI is added to it to help prevent overlapping. Still greater range would give you even more of that, but common levels of wind shift is just starting to get significant at 300 yards, and will make targets harder to read at greater distances unless you get a dead still day. 300 seems to be the best compromise.

The ladder and the OCW are not addressing the same vibration mode in the barrel. There's a good set of FEA model animations on Varmint Al's site showing the 7 major vibration modes. It seems likely from Newberry's description of the occasions an Audette ladder fails and the times his method only finds sets of identical size groups that aren't really all that tight, that the two methods of error nulling need to be in synch to get a real "hummer" barrel. Lack of that synchronization explains why, despite having ammo tuned to throw the smallest possible group, some barrels still have to have tuners added to shoot their best. It would also explain why some powder burn rates produce more accurate loads with particular guns than others. Different burn rates produce different bullet barrel times when achieving the same peak pressures or the same velocities. That difference can be optimized to bring synchronization closer.

 

[ranger335v]

"The round robin is to spread out the influence of fouling and heat in the barrel "

Nick, I can accept all you say. Then I have to say, it doesn't mean a thing to me and, I suspect, a LOT of others. I allow my barrels to cool between shots so heat is of no concern. I get little fouling so, for my limited experiments, I doubt that is a significant factor in my load testing. Certainly shooting at 300 yards would include the verticals from extreme spreads but my chronograph does that anyway.

I'm a southeastern deer and varmint hunter, not a long range sniper. I very rarely see a deer passed 100 yards unless Im driving past private pastures I have no right to shoot over. My own field accuracy limits my crow shooting to 300 yards, usually less. There are a lot of southern hunters limited in the same ways. Therefore seeking better accuracy than about 3" at 300 is as good as we can take advantage of.

My varation of the ladder method at 100 yards (all done so the shots are clearly identified) in small steps while simultaneously ploting velocity against the charge increases allows me to find the accuracy node areas for both powder and seating quite rapidly. I can also see the flattening velocity plateau that suggests a rapidly approaching top pressure even if no other pressure signs have occurred.

Varying my load slightly around those apparent nodes quickly tells me if they're real and, if so, the best way to take advantage of it. I can easily identify the full "window", as I call it, in which small variations don't matter a bit and then I load in the middle so slight variations in charge, seating and temperature are well tolerated and I get few "fliers", if I miss I have no excuse!

Just can't see that following the OCW method, as such, could do me any better. ??

Vamint Al's animated videos on barrel harmonics and whip are a sight to behold ain't they! I've directed several youngsters who (wrongly) perceived barrels as totally rigid pipes to view it and got some amazed feed back.

 

[unclenick]

I should perhaps have mentioned that shooter fatigue and wind changes are among the other influences that are averaged out in the round robin. I also like that you have to shift position slightly on the bags for each target, so each shot is more like a first shot. This is just as compared to shooting the groups sequentially, as you mentioned, and makes no comparison to the ladder. Other than the slight bag shift, it takes no more nor any less time or effort to shoot the round robin than the same number of rounds on each target serially.

If you like the ladder method, I don't see why you shouldn't use it. Many if not most shooters have only 100 yard fixed sight-in ranges at their clubs and can't use the ladder effectively, so I think the round robin is their best option. If you followed my link and looked at my posts on Grit's ladder, starting with #13, you'll see why many folks have technical problems distinguishing their shots as you have been able to do on your ladders. That's a complication that looking at round robin groups avoids.

I've been using both round robins and ladders with tuner weights on my A-bolt's BOSS threads to synchronize the nulls in the two types of barrel perturbation. I suppose, like most accuracy enthusiasts, I do it just to do it and see what it will accomplish and to learn a little more about ballistics. I am specifically interested in what makes a hummer barrel and in why benchrest shooters have had to go to barrel tuners when they are already shooting match loads. I think the answer lies in having to synchronize nulls. It's like any other hobby that way. But if that sort of thing doesn't appeal to you, then it's a waste of your time and ammunition.

BTW, it doesn't necessarily take less time and effort to shoot a ladder. Chris Long says feedback about his node calculator indicates it is almost always within a couple of percent on barrel time. If you have QuickLOAD to work out barrel times to match his node calculations, you can complete a round robin with just 18 rounds. Considering that you don't have to even look through your spotting scope between rounds, it seems to me about as fast as the ladder, and spotting the winner is quicker. You do need more target centers, though.

 

[ranger335v]

"many folks have technical problems distinguishing their shots as you have been able to do on your ladders. That's a complication that looking at round robin groups avoids."

I make a series of numbered targets for my ladders before I go to the range for load testing. One target for each shot, most commonly on 3x5 file cards. After firing, I overlay them and make a composite target. That way, keeping individual shots marked and numbered correctly is certain (and the small composite target is retained in my permanant load test records).

Given the time I take between shots, neither barrel heat nor switching the aim point for each target is any more significant that doing the round-robin thing.


"it doesn't necessarily take less time and effort to shoot a ladder."

True, so far as that goes. Especially if we shoot at what most might consider a "normal" pace. But string time and/or rate of fire is a moot point to me. As a hunter, the only accuracy that matters is what comes from a cool barrel. During load testing I open the actions and allow the barrels to cool to near ambient between shots no matter what development method I follow.

Sure, it takes me LOT more time to shoot for load development than might otherwise be true but I'm convienced a slow paced load development practice should be universal, maybe excepting match shooters! But I haven't done any of that stuff for years so I only shoot from cool barrels now.


"I've been using both round robins and ladders ...to synchronize the nulls in the two types of barrel perturbation."

Not sure I understand; a given load should be giving the same results and perturbing the barrel ( ) the same no matter how it was derived. ??

 

[unclenick]

What I meant by not taking more time was that it doesn't necessarily require more shots be fired to complete the exercise. Not that there was a different rate of fire or anything else. I reject the idea that barrel temperature is the only variable you are trying to even out in the round robin. Fatigue, light conditions (particularly with iron sights), and wind conditions all count too. So does fouling, especially if you are cleaning every ten or twelve rounds as benchresters and military snipers normally do. And even if none of those influences existed, the round robin would tend to mitigate the influence of any others you may have failed to identify. It's just a good scientific variable control.

You're correct that a given load will give the same result under the same conditions, regardless of how you arrived at it. My point is that because you are looking at two independent error sources that require independent tuning criteria to nullify, tuning for either one won't get you groups as small as you could get if their timing were made coincident. In other words, you may find a sweet spot by either method, but neither is necessarily up to the potential of your gun when all the ducks are truly in a row.

As a hunter you may not care about tuning that tightly. It's a hobby bug that either bites you or it doesn't. Jeff Cooper thought emphasis on extreme accuracy was misplaced from the standpoint that the same time spent chasing maximum accuracy would be more productively spent practicing field positions and snap shooting. Beyond a point, those skills have more to do with putting meat on the table than the last quarter of an moa off your group size does. But, once the accuracy bug bites, it's hard to ignore.

 

[rifter]

After seeing many of Nick's posts espousing the "Optimum Charge Weight" method of load development by Dan Newberry, I finally got around to reading about it here:

OCW Overview - Dan Newberry's OCW Load Development System

Dan's observations on methods of picking accurate loads were an eye-opener to me. What absolutely convinced me of his methodology was the further work by another experimenter, Chris Long, whose work can be found here:

Techshooters Shooting Pages

While Chris' writing may be a bit much for the casual plinker, it is refreshing to get some actual theory behind why something may or may not work. As opposed to, say, a bunch of half-truths and myths that have been repeated for the better part of a century - the all-too-common "output" of what passes for the majority of gun magazines these days. Naturally, not all writers have an engineering background; and certainly, very few engineers I know can write worth a darn. But, they *ought* to occasionally get together and vet each other's work.... OK, rant off.

I suggest giving both a read, if you can stand this sort of detail. To save Nick a lot of typing in the future, this post is going to be made into a "sticky" to see if it helps people. I would also like to get commentary from others who have started using these methods.

I have my own questions about applying the method, especially with cast bullets and compressed loads, but am going to mull those over in my head for a bit first.

Discussion on....

Wow! Didn't know there was a name for it. I've been using that method and didn't even know I was doing it. Used the chronograph to get into the ballpark velocity wise, then start tinkering with the charge weight. When I was working up loads for a 7mm-08 to be used for silhouette with a 162 gr. BT match bullet, I got a good load that was pretty consistent but it would throw a round off into the south 40 about every 10 rounds. Drove me nuts, because it always seemed to happen when I trying to tag that last ram at 500 meters. So, I started tinkering, and ended up adding a grain and a half to the load. It tightened things right up, and gave me an increase in my score because I didn't get those **** flyers anymore.

Still have a coffee can full of those loads. Unfortunately, I don't have the rifle any more!

 

[lpreddick]

i am new to this site and am enjoying every visit. i am a varmint (ghog) hunter and obsessed target shooter. i stumbled upon chris long's paper on the shock wave theory of accuracy and a light went on! i chased powder charge changes for years and on occasion arrived at an accurate load after about shooting out a barrel. it is easy to see group size and location change when changing seating depth by .005 thous leaving powder charges unchanged. i have been able to get all my rifles to cloverleaf or better using this technique. however, i have noted that an accurate load after awhile will start to throw one or just open up, even if these rounds were loaded at the same time! as noted during the houston warehouse days, neck tension will affect group size about as quickly as seating depth changes( more on this later) we hear of "accuracy nodes" being related to muzzel velocity more frequently than seating depth. i suspect that seating depth and muzzel velocity are achieving the same thing...getting the bullet to the muzzel when the shock wave is at the action of the rifle(chris long's premise..shock wave theory of rifle accuracy). shooters that "jam" all bullets adjust powder charges until the "accuracy node" is found...velocity now gets bullet to muzzel while shock wave is at reciever. neck tension variation seems to alter pressure, thus velocity and alters this relationship. after years of using seating depth to find the node, i'm now trying jamming bullets about .020 thou into lands and adjusting powder charges to find the node. neck tension variations may not be as big a variant since all bullets are now under about the same resistence to leaving the case. also seating depth measurements can be a bear. neck tension variation and seating depth variation make jumping bullets to find the node more problematic. jamming seems to make these two variables less so leaving powder charge adjustments the key to finding the node. of course we have no control over the other 2000 variables affecting accuracy. i'll keep trying.