Typically what i see for standard load development is some sort of OCW test where they go form min to max charge and find nodes or flat spots in velocity. So they are tuning a specific bullet to exit the barrel at consistent speed and at the optimal time in the barrels harmonic wave. Then once they have found their optimal charge weight they do seating depth. Usually in .003-.010 increments and find the seating depth node, then if that has low sd/es and a good group thats their load. But the problem for me is If you have already found an optimal charge weight at a specific seatting depth lets say Jam -20k or 10 thou off lands what ever seating depth used for OCW then if you change that is it not going to change pressures, velocity, harmonics? If you change seating depth that changes case capacity, jump, jam, pressures and velocity. So if you already found the best velocity for lowest vertical dispersion isnt changing seating depth going to change your velocity and in turn change when ur bullet leaves the barrel? so what point is there in doing some sort of OCW test if seating depth change is going to change when the bullet leaves the barrel, other than for pressure test? So why not just charge cases with a safe ammount of powder and do alot of seating depth test and never change powder charge, just stick with the same one given no pressure signs? What do you guys think of this because i find it hard to belive that charge weight is vertical spread and seatting depth is horizontal spread.
- Thread starter Blake940
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In case you hadn't seen this yet, some more food for thought on load development approaches.
www.shortactioncustoms.com
Bullet Jump Research
www.shortactioncustoms.com 
Or just stick with .02” off the lands, find a charge weight that shoots better than you in any position other than prone, and get on with shooting for more than the purpose of making cases empty for more load development... 
Not sure where or who says powder is vertical and seating is horizontal. That’s nonsense and is likely something passed around from times we didn’t understand as much as we do now.
The only affect powder will have on bullet placement is:
At distance as it’s basic math that a slower round will impact lower than a faster round. The key in loading is to keep the ES small enough for the desired target size and distance.
When using to time the harmonics. This happens when someone picks a seating depth and then uses powder charges to adjust group size. It can work, but I prefer to pick a powder charge and then adjust seating depth to reign in the group size.
Unless making some extremely large seating depth changes, you seating depth won’t change capacity enough to screw up your powder charge. Basically if find a charge weight that has 2850fps and 15 ES with .020 jump, it will still have 15 ES and 2850 with .060 jump.
I personally use a chrono to find my powder node without using any groups to analyze. Then I use the chosen powder charge and find a seating depth node.
I just completed load development with a new 6.5-284. I have found that changes to jump/COAL produced a much larger difference in pressure/velocity than I would have expected:
156gr Berger EOL
57.5 Retumbo: 2975, 2986, 2990 (ejector mark)
Same Charge weight with COAL increased .043:
2917, 2914, 2922
Everything can affect everything, to an extent. In GRT if you change seating depth in a Dasher by 0.020" it changes velocity by 8-10 fps. Certainly it is well documented that choice of powder, primer, and brass can change group size, POI, and velocity spread. If you read Tony Boyer's book he talks about tuning both seating depth and powder charge together, because they are not independent variables.
However, he had the advantage of using a cartridge with a vast amount of collective experience, so he was searching a pretty small space. If we tested everything then we would burn out our barrels before finding an optimal load. As DThomas noted, if you are using a reasonable cartridge with high quality components, then things should tend to work pretty well.
A lot of load development practices are driven by spurious observations due to ignorance of statistics. I highly suspect that if you shot 50 rounds of the average handload against 50 rounds of really good factory ammunition, there would be no difference in group size or SD. If you are shooting long range benchrest or F class, then you do have to get into these details and try to figure out what is BS and what is real. But for PRS you aren't going to see the difference on target anyway.
However, he had the advantage of using a cartridge with a vast amount of collective experience, so he was searching a pretty small space. If we tested everything then we would burn out our barrels before finding an optimal load. As DThomas noted, if you are using a reasonable cartridge with high quality components, then things should tend to work pretty well.
A lot of load development practices are driven by spurious observations due to ignorance of statistics. I highly suspect that if you shot 50 rounds of the average handload against 50 rounds of really good factory ammunition, there would be no difference in group size or SD. If you are shooting long range benchrest or F class, then you do have to get into these details and try to figure out what is BS and what is real. But for PRS you aren't going to see the difference on target anyway.
That's exactly what Bryan Litz recommends now.
Yeah, I've seen that statement many times, and I agree it has to be a gross oversimplification.
The other funny thing to me about "just use seating depth for group size" is that many modern bullets are highly insensitive to seating depth. So if powder charge doesn't matter and seating depth doesn't matter...
Your whole post here is a contradiction to itself.
First you say powder charge holding vertical is nonsense, then say you use a chrono to find a powder node. What does your "powder node" actually accomplish if it is not removing vertical dispersion from the equation?
One thing that is fact is that chrono numbers and group size shrink in accordance with each other by adjusting powder charges.
I am not here to argue, and think you are partially correct on a lot of it, but like you said, it has a lot more to do with the understanding of barrel harmonics, which was always part of the equation, just not understood by most.
But the single biggest advancements in load development comes with the tools we have available to measure what we do. Labradar and Magnetospeed have simplified the crap out of things. Even 10 yrs ago, one had to be serious about shooting to own a Oehler 35P, today no one bats an eye at 370 for a magneto.
What I am saying, you are basically doing the same thing you dissed in your first sentence, just that you are in a Mercedes on the interstate vs a 1950 ford pu on a gravel road.
You’re interpreting my post incorrectly or I didn’t use the correct words. Either way, I’m saying that vertical dispersion is not *only* a result of powder charge. And horizontal is not *only* a result of seating depth.
I am not sure on that. Answer this, I see you are in a post concerning 109 hybrids, so I assume you have used 105 hybrids also? Does your seat depth in relation to the lands change from barrel to barrel, or case to case?
IME, it does not, not even velocities will change how far off the lands certain bullets shapes like. By me saying this, it would be safe to assume I have not tried SAC's jump test.
I think the vertical is powder and horizontal is seating is being misconstrued from ladder testing/positive compensation goals (whether you abide by this theory isnt my point, just attempting to explain the phrase)
You tune the powder so that you find where the charge weights tighten up on the board at distance. That takes care of the vertical.
And then you tune the seating depth so that the groups themselves shrink down, that takes care of the horizontal.
You tune the powder so that you find where the charge weights tighten up on the board at distance. That takes care of the vertical.
And then you tune the seating depth so that the groups themselves shrink down, that takes care of the horizontal.
D
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1) OCW has nothing to do with any "velocity node". OCW maps gross barrel movement in a sine wave pattern. There will be a point where 2 or more groups in a row will have the same POI in relation to the target.
2) Seating depth maps another harmonic all together. As the barrel is whipping up and down, it is also vibrating in an eliptical pattern and the bore is dilating in and out like a nervous sphincter. Seating depth tunes this harmonic. When doing seating depth, you will notice that the actual center of POI changes very little, if at all, while your groups will elongate and contract.
3) In my experience, the good powder node almost always shows up between 1%-2% off of max pressure. This means that the powder is burning within it's optimal pressure range for a clean, full power burn, and is not hot enough to get pressure spikey when the temp gets hot.
4) There have been some fairly interesting tests done and published on PRB that there is usually a very narrow seating node around .010" off the lands. It is often the best performer, but also the narrowest and finickiest.
5) That same experiment found that there are most often far wider and forgiving nodes starting at .060" off and extending to .100" off. Though they tend to be less accurate overall.
6) Chronograph velocity "flat spots" are shit. They are the random affect of overlapping extreme spreads. They are the equivalent of randomly shooting a 1/4 moa 3 shot group from a 1 moa rifle.
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I thought OCW stood for optimal charge weight. Charges that impacted in the same place on a target, therefore identifying a velocity node.
D
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It does stand for Optimal Charge Weight, but velocity isn't the primary indicator.
If it was, then you would be doing it with a chronograph and looking at numbers rather than looking at the paper.
Love the 1st five points made, but this is where I don't see that as being "shit"...
I feel like ALOT of guys use chrono data to find "flat spots" or charge weights within a certain range that give lower ES over the sum of the charge weights. Then they do this mulitple times with different rifles and loads, and are successful with it.
I feel like if it was "shit"...then guys wouldn't do it successfully and consistently. Seems like just another way to skin the cat...
Your problem is that you do not understand the fundamental point of the Optimal Charge Weight method.
The point is not, as you think, to "tune a load to a consistent speed and a the optimal time in the harmonic wave".
The point is to find a range of charge weights (and by extension muzzle velocities) that will create little to no change in point of impact on target. One then selects the mean of that charge weight range (where the load is most resistant to changing POI with MV variation) and then proceeds to adjust seating depth to reduce group size.
Of course changing seating depth is going to create small changes in MV. But since those changes in MV are occurring within a range that has little to no effect on POI, the end result is an optimal load in precision AND accuracy.
I personally think people who believe in flat spot nodes shoot Hodgdon powders primarily. You wont find many flat spot nodes with VV, Norma, Alliant, or even IMR's new Enduron line of powders. You add powder, the speed goes up, and it takes more than 2 shots per charge to come to any conclusion there.
Being I am not a big Hodgdon fan, though I do shoot Varget and H4895 today, it is easy for me to say, I don't buy in also. Truth is, it seems to work for guys, so I cannot say it is not valid.
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I have found that with Hodgdon, VV, and RL powders, if you don’t find a flat (or at least low enough to not make a big deal) spot......then you change the primers up. You’ll find some flats with a different powder primer combination. Or vice versa. Change the powder and keep primer.
Most times when I see people who don’t find flat spots (not meaning you directly), it’s because they picked a powder and/or primer and wouldn’t deviate from that.
I’m not saying you’re wrong, because honestly I don’t have a lot of experience with all the brands of powder.
I feel like If that we’re true, then to keep ES numbers down, you’d have to weigh your charges with more consistency than a lot of us do, barring the AD FX120, especially if you’re after longer ranges.
It also just doesn’t make sense... if everything is about harmonics and vibration then we aren’t talking about anything that’s perfectly linear. There’s going to be hims and haws in there... “hims and haws” is about as scientific as it gets lol
In your defense, I mainly use H4350 and XBR 8208 but am playing with RL26 now and I’m seeing those same “flat spots” so far. We’ll see how it holds up
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I guess i could see that aspect, if there is one thing I wont vary much from is primers, I shoot 210 &205M's exclusively and work around it. I dabble with CCI 450's some in 6mm small pocket brass, and 223 ammo.
As i said in the post you quoted, I am not a flat spot guy, lol
LOL, hem and haw, hems and haws, hims and hers
I am out, I believe there are many roads to the target, we each take our own.
Also, many times it may not be an obvious flat spot in velocity.
But say your average velocity increases by 12fps per .2 gr of powder.
Across a .6gr window, the three charges had very small ES.
Across the next .6gr window, the ES was much greater.
So, while not an true “flat spot” it was the window in which velocity will remain the most consistent if something changes. And at distance, velocity (and BC) is what’s going to screw you.
But say your average velocity increases by 12fps per .2 gr of powder.
Across a .6gr window, the three charges had very small ES.
Across the next .6gr window, the ES was much greater.
So, while not an true “flat spot” it was the window in which velocity will remain the most consistent if something changes. And at distance, velocity (and BC) is what’s going to screw you.
I would have assumed that anyone who was serious about long range shooting was using an FX120i, Sartorious, or Prometheus. That being said, even with charges that are within 0.02 grains, you still often get an SD fo 8-10, so there are clearly other sources of variation. I'm not sure that "flat spots" or nodes can overcome this.
This is where looking at ES comes into play. You look for areas where the ES of the node (not just single charge) is as low as possible. In theory, if something changed, it would have the least effect on overall velocity.
Though for prs, who gives a shit. The target will eat it anyway.
I’m working on maybe having two “experts,” one who is an OCW fan and another who uses chrono and such......
Have them do load work up on same barrel or at least chambered as close to the same as possible. They both log everything and we compare:
Powder chosen
Primer chosen
Final Charge Weight
Final seating depth
Amount of time spent on load
Rounds fired to find load
In a perfect world, do it with 3 or so different calibers. See if they both get very similar results or it varies wildly.
Have them do load work up on same barrel or at least chambered as close to the same as possible. They both log everything and we compare:
Powder chosen
Primer chosen
Final Charge Weight
Final seating depth
Amount of time spent on load
Rounds fired to find load
In a perfect world, do it with 3 or so different calibers. See if they both get very similar results or it varies wildly.
I like that idea, but I would also add some high quality factory ammo (Berger, FGMM) as a comparison. And the final test has to be at least 20 rounds of each.
I would say the only fair way would be with the same barrel. Fire enough to get through the speed up, clean it, give to guy #1, when he is done, clean, guy #2 gets it, hopefully all completed in under 200 rds.
I think an accuracy test under similar conditions are in order also in your findings
Guys were shooting a long ways before before the fx120i became popular, or auto trickler a thing. Guys were shooting tiny groups at 1K also w/o lab grade scales.
I will say it again, the tools at our disposal just makes things easier, better is subjective to 200 yards.
Exactly what I was thinking ...
Well load development and brass prep play a big role in that too... Because I dump all my charges for my 6.5 out of a CM 1500 and a CM Lite right next to each other, and load all my ammo on a Dillon 550, and my ES is usually in the teen's for 10 shots, and SDs around 5-8.
Hard for me to believe that I "must have" a Sartorius or AD Fx120 to have consistent ammo. Consistent neck tension (checked with Z-pin gauges), and proper load development have treated me well.
Occasionally when my Chargemasters throw a visibly high charge at 0.1gr over, I'll just dump it in the case anyways and see what happens at the range. There were probably 3 of those during my last range session, and I had an ES of 26 over 40 total shots. According to Strelok Pro, thats about 7" of total spread due to velocity at 1000yds.... Not sure I need any better than that for what I'm doing...
The biggest thing I’ve seen with scales like fx120, is that you can load precise/fast enough for PRS that generally speaking, nodes are a bit overrated.
If say you are using a berger 105 and you have a spot on BC for your lot that works with the chrono velocity (meaning you don’t need to tweak velocity for your software to work), then you can literally pick any random charge weight that doesn’t give you pressure issues......load 200 rounds all the same, chrono it, and be perfectly fine for practical shooting.
I’ve been doing this with 109’s recently just to test out how much it (doesn’t matter). My AB custom curve works with whatever the chrono velocity is. I have been able to load up any charge I want and the sd/es may not be the best, but it’s well within the error of our target size. Then just chrono, and go.
Most any modern rifle with modern components will shoot just about everything under an moa and tweaking is done to get down sub .5.
Could you do this with a charge master or beam? Yes, but it won’t be as fast, and at times it might be less accurate than needed for random charge weights vs nodes (again, for PRS type stuff).
If say you are using a berger 105 and you have a spot on BC for your lot that works with the chrono velocity (meaning you don’t need to tweak velocity for your software to work), then you can literally pick any random charge weight that doesn’t give you pressure issues......load 200 rounds all the same, chrono it, and be perfectly fine for practical shooting.
I’ve been doing this with 109’s recently just to test out how much it (doesn’t matter). My AB custom curve works with whatever the chrono velocity is. I have been able to load up any charge I want and the sd/es may not be the best, but it’s well within the error of our target size. Then just chrono, and go.
Most any modern rifle with modern components will shoot just about everything under an moa and tweaking is done to get down sub .5.
Could you do this with a charge master or beam? Yes, but it won’t be as fast, and at times it might be less accurate than needed for random charge weights vs nodes (again, for PRS type stuff).
Submitting my application for free barrel and loading components soon.
D
Deleted member 113831
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If you take note:The vast majority of people that are finding these "flat spots" that are continually panning out, are shooting small to medium capacity 6mm's or 6.5mm's. These types were designed to be easy to tune, because most of them have their roots in the benchrest game. You look at OCW's with these cartridges and POI across the entire test might vary 0.5" at the outside. They will basically shoot anything you feed them with differing degrees of "wonderful".
Try this with a sporter weight 30-06 or a 300 Winmag or even a 270 Win and tell me how it works out for you. You might get lucky, odds are that you won't.
I don't trust any method exclusively. I usually do a cursory ladder test, mostly to find pressure signs, but also will look for indicators of optimal charge. Then I'll pick am area of about 8 loads to try. I'll do 5 loads of each and shoot for groups and also record velocities. The loads that shoot the best groups have the lowest es/sd. But off you only shoot 1 round of each you would end up with random flat spots in your data. You need a larger sample size to have true results. There is no short cut.
There are too many inaccuracies in this post to address.
The better your brass prep and QC of your process, the less rounds for accurate data.
The best groups don’t always have the best chrono numbers. Etc etc
You should check out Gordon’s Reloading Tool (GRT) which is something I am looking into currently and a) I am impressed so far, and b) I really believe this has promise. It is a software program (free download) that is based around optimal barrel time. The theory seems sound, and the software seems equally sound so far.
@Bbracken667 the OP in the thread hasn't been seen since 2020.
If you place your cursor over the poster's avatar, you can see the last time they checked in.
If you place your cursor over the poster's avatar, you can see the last time they checked in.
You are right about statistical errors. 3, 9 or 15 rounds is just not a statistically significant population. If you are shooting at least 35-50 rounds for a given charge/seating depth then your data is suspect. You may luck out and pick the right group or maybe not. There is enough random variation built in that 9 or 15 rounds as a sampling size is just entirely inadequate.
Frankly, if I can’t surpass factory ammo in accuracy then I would just hang it up. There are enough opportunities to fine tune that that should not be an outcome.
But seriously, statistically the “average” approach to development is just a shot in the wind.
If you don’t believe me: shoot 5 rounds. Collect SD and ES. Then shoot 50 rounds same exact load and calculate SD and ES and see if they are the same, or even close to the same.
Or just ask a statistician if you know one.
What the heck… I wonder how this popped into my feed as a new reply to a discussion I was following? I guess I need to pay closer attention LOL
Thanks for the heads up. Confused but slightly better informed now ….
