Selecting powder nodes from chronograph/SDs/flatspots - What am I doing wrong?

[!Peter!]

Below are the results of some of my testing: Weight vs Average Speed and ES. This was done with 5 shot groups.

I suppose you could say there's a flattening of the velocity between 43.5 and 44. Or that 43.5 had a higher average velocity than the general trend. Either way, I don't see it as statistically significant enough nor have a significant enough correlation with group size, shape or centre location to investigate further.


I use ES and the groups shot at each weight to chose my load.

 

[RegionRat]

This is what I'm not grasping....
Shots 17&18 are plotting a flat spot in velocity but vertical on target.
Shots 15&16 are plotting vertical but horizontal on target.
Sharing load tune information with another member I've seen his chronograph #'s for charges shot against the target. I remember 1 target in particular 3 shots per charge, one of which had the same velocity for all 3 shots but a very open grouping, whereas a charge with a variation in velocity of 6-8fps grouped the smallest.

Some parts of harmonics are compensating in our favor and others are not. This is just a sweep of charge using one sample per charge weight. As mentioned above, if you ran them say five different times, you would see the SD/ES at some points was small and at others large. In the charge ladder the way I display that sweep, what @Ned Ludd was pointing out was that we don't always get a flat spot in velocity but we almost always see several charge steps where the vertical component goes flat or even drops before starting to climb again.

What we are hoping to find is a node that is several steps wide in terms of vertical, without a steep change in velocity. That node in the middle of the sweep starting at about 31.4 is about one grain wide. If we take a risk on a single sweep, it is a fairly easy thing to check a seating depth sweep using a charge in the middle of that range, and then run group tests to verify all those assumptions.

Keep in mind that this was a 6 Dasher with a Palma barrel section. This was too easy compared to many other guns. This is like hitting the easy button, but don't expect guns with lighter barrels and flimsy stocks to be as clear when reading their plots.

 

[Ned Ludd]

That's a very interesting analysis; appreciate your contribution as always. If I were just looking at the spreadsheet I'd say park it at 31.65gr and call it good. With the shotmarker data added to it, I'd run it at 33gr and not give it a second thought.

I'm probably going to steal this. I assume you manually input the data into excel? There's no way to easily export from your LR and shotmarker?

Edit: Somewhat related, I've found enabling the mean radius stat on my SM really helpful. Noticed you don't have it on; figured I'd make mention.

Either one of those regions looks like it represents a nice accuracy node. Obviously, the lower node is a little wider. My choice would also be influenced by how close to MAX pressure the upper node is. Not loading for the Dasher, I have no feel for that from the velocity data. The most important aspect in terms of your original post is that neither one of those nodes corresponds to a "flat spot" in the velocity curve. Granted, those are individual velocity values for each shot in the ladder, but doing multiple identical ladders in order to gather more velocity data at each charge weight would not have guaranteed any different result with respect to the presence of a "flat spot" in the velocity curve. Thanks for posting those results, RegionRat.

 

[RegionRat]

No worries Ned, I already ran those plots to answer a question similar to this thread several months back.

If the winds die down to less than 50 MPH, I'll be heading back out to the range to run similar load development work on a brand new barrel, but this one will be 223.

I'll run another wide sweep for charge and seating depth, then follow up with more samples near the range where I know I will load. I'm typically 24 grains of RE-15 or Varget plus or minus a smidge, but for the sake of the folks who want to see this stuff and to break in the barrel, I'll add the data. I'm only saying that because this is a 223 and I have the material. Otherwise, I would be able to go straight to where I already know the charge and just check seating depth.

An underlying concept here, is that some of us have nearly standard habits with barrels, reamers, bullets, powders, etc., so with these match barrels there is little surprise or doubt in the outcome when we risk making decisions on very few shots.

This would not be the case for a light sporting barrel and stock designed to be packed up and down the hills, especially one with an unfamiliar reamer, barrel profile, or stock. The match barrel above can shoot a whole string without getting very hot, but a sporting barrel must be tested at a much slower pace to keep from getting red hot. That makes the patients level requirement go way up for the same test.

 

[davidjoe]

I don’t believe in flat spots. Anytime one has presented in a load test, it hasn’t been there again any other time the test was duplicated. I see a very direct correlation in rise of velocity with increase in charge weight. Certain charges will have better ES/SD than others, but there is no flat spots in velocity.
View attachment 1259555

In general I’d agree that more powder equals more velocity on a predictably straight line or predictable curve. I don’t think we see load or pressure apps programmed to predict flats or peaks in the powder inputs versus velocity outputs.

I’m not certain that at the individual gun level the line is always perfectly smooth and flat, though, just as with horsepower curves, (combustion pushing cylinder through bore, measure output, except round trip) there are small RPM ranges, that while higher from more combustion, didn’t produce exactly as much more horsepower as would be expected, (notches) for reasons unique to the mechanical characteristics of that engine. Some very good engines have basically none. An aside, engines also do eventually produce less horsepower even though the RPM’s have continued to increase, on the way to red death, which I think is where I must run my rifles.

My personal suspicion though is that the notches or flat spots would be found at different loads with temperature changes, based on seeing velocity spans in the course of a day and even in strings, also that barrel wear within a match or two would move or erase those notches, such that they are probably not repeatable. Also, this level of load specificity truly would rule out loading ammo in the thousands (rainy day 2021) for barrels not even on guns yet, or even your other current guns, which I’ll admit to being about half of what I shoot, especially at club level, and probably that does make my opinion biased.

 

[davidjoe]

Flat spots do exist. As has been noted by others, those flat spot may or may not align with the vibrational behavior of the rifle in whole. When the two marry up, it's like magic. Otherwise, it's a waste of time.

I tune by POI, but chrono at the same time to look to see if I'm in a flat spot, because that tells me if my ES/SD is going to be good or not. Sometimes, the picture in the crystal ball is cloudy, and good POI happens too frequently. I sort that out by velocity flat spots.

I always verify at long range, anything I decide at short range.

Hey Keith, very much enjoy the YouTube videos. 100% with you on recent one about close range testing for tune instead of distance where weather is a factor.

So a narrow question, … why is it that sometimes, as you mention above, a group (poi) is perfectly good - the 0’s, when ES of the group isn’t tight enough to really explain how the group (including vertical component) is so good?

 

[BP1]

I tend to agree with this observation; it's mostly PRS guys trying to have chronograph battles with each other. That said, I have also noticed a few of the big named F-Open folks claiming to do it for their load dev. I'm not going to call them out by name, but I've seen them make mention of it here, as well as on the YouTubes.

I don't think these guys are saying it to mislead either; I genuinely believe it works for them...so I'm left to assume that I'm doing something wrong.



Hah! That's hilarious. I don't want to make anything better, I just want to arrive at the same conclusion while expending fewer primers on new tubes/new cartridges.

Mike no waste primer. Mike want answer faster. Mike seek answer smart people.

Mike I hear ya on the..no waste primer..want answers faster..seek smarter people. That’s why I call Jason and say Hey bro what load you shootin oh ok thanks..then I’m done.

 

[MikeMcCasland]

I'm both surprised and disappointed nobody is jumping in to defend the use of a chronograph for powder node testing. I see this methodology recommended on here all the time; maybe less often here than on various FB groups, but it's for sure talked about.

This wasn't a call out thread either; I was genuinely hoping to short-cut the load dev process.

Not that big a deal on my .308s, but for other cartridges it would make a big difference.

Mike I hear ya on the..no waste primer..want answers faster..seek smarter people. That’s why I call Jason and say Hey bro what load you shootin oh ok thanks..then I’m done.

BP1 - Now there's an idea. Can I borrow your reamers too? Now we're really saving time & money.

 

[Jdne5b]

Do the people using that method use a tuner?

Do you have the data from your test where you came to the 44.3 conclusion? Where does 44.6 fall, how much faster? Is the the same velocity as it was in the original test?

 

[MikeMcCasland]

Do the people using that method use a tuner?

Do you have the data from your test where you came to the 44.3 conclusion? Where does 44.6 fall, how much faster? Is the the same velocity as it was in the original test?

I don't know about the tuner; that's a good point though.

As far as my data, I don't have the first set of data for when I settled on 44.3 (at least the velocities). I've started doing all my load dev at the range, so my recording of data back at home is less than it used to be...especially with TR barrels.

That said, I do have my data from this past Saturday. It's "flat spotting" at 44.2-44.4 for both CCI primers, and jumping pretty significantly at the 44.6 node. That said, 44.6 was definitely better with both CCI offerings. This barrel hates 205Ms for whatever reason.



Edit: I am 99.9% sure the velocities are the same as the first time around.

 

[RegionRat]

Here ya go. This is your data plotted up. Velocity on the left, then one chart with the SDs on the right, and the next with the MOA on the right.

 

[MikeMcCasland]

Region Rat - Thanks for putting that together. That's an interesting view. I use conditional formatting as an easy way to see it...and mostly because I'm too lazy to chart out my load dev sheets, but that's really interesting. Just a graphical representation of what I'm saying. Accuracy doesn't seem to correspond to any velocity flat spots.

That said, you got me thinking. There's probably a lot of money to be made for someone who can develop a reloading database that captures all this structured data in a standardized format, then ports it over to like PowerBI or Tableau etc.

As a whole, we (the precision shooting community) generate so much structured data, with so much overlap and commonality between shooters...that if aggregated and put into an easy to digest graphical format...it would make load dev insanely easy.

Precision Rifle Blog pseudeo plays in this space for the PRS guys, but it's nothing like what it could be.

Any retired DB developers and PowerBI experts want a side project? I will invest lol.

 

[RegionRat]

Our own @F Class John recently did a demo of a canned program that "reads" your data and plots it. They called it ChronoPlotter.

None of these are truly completely automatic, but for folks who are averse to learning Excel, MatLab, etc., this is an option if you are running MagnetoSpeed or LabRadar for your chrono.

I just don't find it difficult to cut and paste those columns from the LR or MS and graph them. Especially if I don't need to present them to anyone else, since then I don't bother with titles, labels, or legends.

The only interactive input is due to the fact that the instruments and the graphing program have no way to know what you loaded in terms of charge, seating depth, or whatever else you are testing, so you still have to learn to put that information into the program. (Hint to MagnetoSpeed, LabRadar, and ShotMarker, it wouldn't take much to have a routine that tagged that data with a user input during a test run.)

I run all my notes into an Excel file per barrel or gun. Since all that is kept with the raw LR and ShotMarker data per session, it is no big deal for me to plot things that need a little study.

Admittedly, programs like MimiTab, MatLab, Excel, etc., are not free or cheap, so if you don't swim in those pools I can't give good advice other than to have a club-mate run your data for you when you need it. In my time, we were always prepared to work with a sliderule, pencil, and piece of paper cause they couldn't always give us electrical power in many places. I don't panic if I don't have these tools, but I will also add that it makes data analysis nearly automatic.

 

[Keith Glasscock]

Hey Keith, very much enjoy the YouTube videos. 100% with you on recent one about close range testing for tune instead of distance where weather is a factor.

So a narrow question, … why is it that sometimes, as you mention above, a group (poi) is perfectly good - the 0’s, when ES of the group isn’t tight enough to really explain how the group (including vertical component) is so good?

You mean at short range? For the most part, we give velocity too much credit for variation in POI. Once free of the bore, all things fall at the same rate...

IMO, There is a lot we don't know about how vibration affects not only where the bore is pointed at the instant of bullet release, but also the impact on trajectory of muzzle blast effects and bore motion on bullet dynamics in the first few feet of bullet flight. I'm suspicious that gyroscopic precession has a bigger role to play than we give it credit for.

 

[BP1]

Region Rat - Thanks for putting that together. That's an interesting view. I use conditional formatting as an easy way to see it...and mostly because I'm too lazy to chart out my load dev sheets, but that's really interesting. Just a graphical representation of what I'm saying. Accuracy doesn't seem to correspond to any velocity flat spots.

That said, you got me thinking. There's probably a lot of money to be made for someone who can develop a reloading database that captures all this structured data in a standardized format, then ports it over to like PowerBI or Tableau etc.

As a whole, we (the precision shooting community) generate so much structured data, with so much overlap and commonality between shooters...that if aggregated and put into an easy to digest graphical format...it would make load dev insanely easy.

Precision Rifle Blog pseudeo plays in this space for the PRS guys, but it's nothing like what it could be.

Any retired DB developers and PowerBI experts want a side project? I will invest lol.

Mike at the end of the day..believe the target and don’t give a rats azz about numbers..trust me the stress isn’t worth it.

 

[davidjoe]

You mean at short range? For the most part, we give velocity too much credit for variation in POI. Once free of the bore, all things fall at the same rate...

IMO, There is a lot we don't know about how vibration affects not only where the bore is pointed at the instant of bullet release, but also the impact on trajectory of muzzle blast effects and bore motion on bullet dynamics in the first few feet of bullet flight. I'm suspicious that gyroscopic precession has a bigger role to play than we give it credit for.

Precession similar to the path a spinning top can trace as it goes into or out of stability, yes. I have seen videos of spinning bullets leaving a muzzle rotating as they go forward around an axis line such that they had a probability of impacting anywhere along a clock’s face until they stabilized, and blast seem to jilt the tail.

I’m like Otis on the paper holes being the litmus test, but at each point before the impact something just prior determined that position, and so on, which is interesting to chase down.

 

[JayBeeYou]

Mike,
Come on down to San Antonio, I will give you a class on how to really reload your ammo and find the perfect load.

 

[MikeMcCasland]

Mike,
Come on down to San Antonio, I will give you a class on how to really reload your ammo and find the perfect load.

This otta be good....The JayBeeYou school of precision reloading... let me guess the curriculum.

Lesson 1: Lots?!? Just mix that shit together!
Lesson 2: Dillion Dies: The choice of the discerning F-Class professional.
Lesson 3: Chargemasters: Only need to load to the nearest whole number anyway.
Lesson 4: "It's probably about 2650. Dial 30 minutes in and see what happens"

J/K - Please don't beat me too badly next match.

Hugs and Kisses,
Mike

 

[JayBeeYou]

This otta be good....The JayBeeYou school of precision reloading... let me guess the curriculum.

Lesson 1: Lots?!? Just mix that shit together!
Lesson 2: Dillion Dies: The choice of the discerning F-Class professional.
Lesson 3: Chargemasters: Only need to load to the nearest whole number anyway.
Lesson 4: "It's probably about 2650. Dial 30 minutes in and see what happens"

J/K - Please don't beat me too badly next match.

Hugs and Kisses,
Mike

Must be getting old and forgetful, sounds like I already learned you up.

 

[Sandstorm]

I do my initial tune from flat spots and the fine tune with seating, and what the target tells me
will override the rest...however its been darn close and at distance as well..hmmmm
so....more testing on this subject needed...as always.
Never ending black hole..lol